TJ A/C Issues
 

It's been a while since I've posted to this newsgroup, but this latest
issue has brought me and my repair shop to a standstill. This takes
place with my 1997 TJ. Put as simple as possible, the problem is
that, on occasion, the A/C refuses to get remotely cold after any
length of time (primarily on hot, humid days after the car was sitting
outside). Living in South Florida, days like this are quite common.
Now, the clincher is that it is not constant. If the vehicle is
sitting in a garage, or is started on a cooler day, the A/C gets very
cold, measured at my shop to 40 degrees, which is exactly what I'd
like to always happen. On those hotter days, it doesn't matter if the
car is idling, driving stop and go, or on the highway; the air will
simply not get below about 65-70 degrees through the vents, at best.
To address the issue, all A/C hoses were replaced to avoid a prior
problem of the system freezing (ice falling off hoses when the car
stopped), the low pressure switch was replaced, as was the evaporator
and accumulator. The condenser was thoroughly cleaned as well. It
was checked for leaks, and recharged three times, with the same
results. The fan is fine, and the compressor is a non-cycling model
(from what the shop says, at least), and stays on when it should.
Since the shop keeps their current repairs in a garage, the A/C works
fine for them, but then has the same problems outside when I leave.
Does anyone on here have any suggestions on other things to check?
Since the summer is in full swing, I'd really like to get this A/C
problem finally fixed. Thanks for anything you've got.
Joe Winn
Florida
'97 Jeep Wrangler Sport - Flame Red

Re: TJ A/C Issues
 

Joe writes:

> Does anyone on here have any suggestions on other things to check?

You may have an incompetent repairman. Ice anywhere on an A/C system is
solid evidence of malfunction.

Replacing hoses to fix icing?!?!?! Who swindled you on that?

A refrigerant undercharge is (paradoxically) one cause of icing. An
undercharge will also behave as you describe, working OK in light loads,
but not keeping up with more heat and/or humidity. So will a
restriction in the system.

Why was the low-pressure switch replaced? More guessing at your
expense?

When you have the evaporator and accumulator replaced, you should have
demanded a vacuum leak test, where you actually personally get to watch
the gages and see them hold a vacuum. So many A/C techs are incompetent
or will wave off a slow leak because they make believe it is fixed or
won't matter.

If you've paid as much as I think you have for this work, then you
should have been shown performance test results per the service manual.
None of this wave-of-the-hand-your-done.

A/C work is absolutely the worst to hire out. Huge prices for guys who
pretend to know something they don't. That's why I learned to do it all
myself.

Re: TJ A/C Issues
 

Joe writes:

> Does anyone on here have any suggestions on other things to check?

You may have an incompetent repairman. Ice anywhere on an A/C system is
solid evidence of malfunction.

Replacing hoses to fix icing?!?!?! Who swindled you on that?

A refrigerant undercharge is (paradoxically) one cause of icing. An
undercharge will also behave as you describe, working OK in light loads,
but not keeping up with more heat and/or humidity. So will a
restriction in the system.

Why was the low-pressure switch replaced? More guessing at your
expense?

When you have the evaporator and accumulator replaced, you should have
demanded a vacuum leak test, where you actually personally get to watch
the gages and see them hold a vacuum. So many A/C techs are incompetent
or will wave off a slow leak because they make believe it is fixed or
won't matter.

If you've paid as much as I think you have for this work, then you
should have been shown performance test results per the service manual.
None of this wave-of-the-hand-your-done.

A/C work is absolutely the worst to hire out. Huge prices for guys who
pretend to know something they don't. That's why I learned to do it all
myself.

Re: TJ A/C Issues
 

Joe writes:

> Does anyone on here have any suggestions on other things to check?

You may have an incompetent repairman. Ice anywhere on an A/C system is
solid evidence of malfunction.

Replacing hoses to fix icing?!?!?! Who swindled you on that?

A refrigerant undercharge is (paradoxically) one cause of icing. An
undercharge will also behave as you describe, working OK in light loads,
but not keeping up with more heat and/or humidity. So will a
restriction in the system.

Why was the low-pressure switch replaced? More guessing at your
expense?

When you have the evaporator and accumulator replaced, you should have
demanded a vacuum leak test, where you actually personally get to watch
the gages and see them hold a vacuum. So many A/C techs are incompetent
or will wave off a slow leak because they make believe it is fixed or
won't matter.

If you've paid as much as I think you have for this work, then you
should have been shown performance test results per the service manual.
None of this wave-of-the-hand-your-done.

A/C work is absolutely the worst to hire out. Huge prices for guys who
pretend to know something they don't. That's why I learned to do it all
myself.

Re: TJ A/C Issues
 

Joe writes:

> Does anyone on here have any suggestions on other things to check?

You may have an incompetent repairman. Ice anywhere on an A/C system is
solid evidence of malfunction.

Replacing hoses to fix icing?!?!?! Who swindled you on that?

A refrigerant undercharge is (paradoxically) one cause of icing. An
undercharge will also behave as you describe, working OK in light loads,
but not keeping up with more heat and/or humidity. So will a
restriction in the system.

Why was the low-pressure switch replaced? More guessing at your
expense?

When you have the evaporator and accumulator replaced, you should have
demanded a vacuum leak test, where you actually personally get to watch
the gages and see them hold a vacuum. So many A/C techs are incompetent
or will wave off a slow leak because they make believe it is fixed or
won't matter.

If you've paid as much as I think you have for this work, then you
should have been shown performance test results per the service manual.
None of this wave-of-the-hand-your-done.

A/C work is absolutely the worst to hire out. Huge prices for guys who
pretend to know something they don't. That's why I learned to do it all
myself.

Re: TJ A/C Issues
 

On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
> Joe writes:
> > Does anyone on here have any suggestions on other things to check?
>
> You may have an incompetent repairman. Ice anywhere on an A/C system is
> solid evidence of malfunction.
>
> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>
> A refrigerant undercharge is (paradoxically) one cause of icing. An
> undercharge will also behave as you describe, working OK in light loads,
> but not keeping up with more heat and/or humidity. So will a
> restriction in the system.
>
> Why was the low-pressure switch replaced? More guessing at your
> expense?
>
> When you have the evaporator and accumulator replaced, you should have
> demanded a vacuum leak test, where you actually personally get to watch
> the gages and see them hold a vacuum. So many A/C techs are incompetent
> or will wave off a slow leak because they make believe it is fixed or
> won't matter.
>
> If you've paid as much as I think you have for this work, then you
> should have been shown performance test results per the service manual.
> None of this wave-of-the-hand-your-done.
>
> A/C work is absolutely the worst to hire out. Huge prices for guys who
> pretend to know something they don't. That's why I learned to do it all
> myself.

First, thanks for the rapid reply. All of those repairs were done in
one fell swoop as a comprehensive repair to stop the system from
freezing up, and subsequently, restricting air flow through the vents,
especially after being at highway speeds for more than a few minutes.
This shop has always been competent in other repairs, but this A/C is
seemingly giving them a lot of trouble. Since, as you guessed, I did
end up paying a decent amount for it all, I'm bringing the car back in
for a third time to hopefully get it completely fixed. I will demand
to see the results of the vacuum test to make sure there are no leaks,
and also make sure their charge is adequate.
Hopefully this debacle will finally end. Thanks again.
Joe

Re: TJ A/C Issues
 

On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
> Joe writes:
> > Does anyone on here have any suggestions on other things to check?
>
> You may have an incompetent repairman. Ice anywhere on an A/C system is
> solid evidence of malfunction.
>
> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>
> A refrigerant undercharge is (paradoxically) one cause of icing. An
> undercharge will also behave as you describe, working OK in light loads,
> but not keeping up with more heat and/or humidity. So will a
> restriction in the system.
>
> Why was the low-pressure switch replaced? More guessing at your
> expense?
>
> When you have the evaporator and accumulator replaced, you should have
> demanded a vacuum leak test, where you actually personally get to watch
> the gages and see them hold a vacuum. So many A/C techs are incompetent
> or will wave off a slow leak because they make believe it is fixed or
> won't matter.
>
> If you've paid as much as I think you have for this work, then you
> should have been shown performance test results per the service manual.
> None of this wave-of-the-hand-your-done.
>
> A/C work is absolutely the worst to hire out. Huge prices for guys who
> pretend to know something they don't. That's why I learned to do it all
> myself.

First, thanks for the rapid reply. All of those repairs were done in
one fell swoop as a comprehensive repair to stop the system from
freezing up, and subsequently, restricting air flow through the vents,
especially after being at highway speeds for more than a few minutes.
This shop has always been competent in other repairs, but this A/C is
seemingly giving them a lot of trouble. Since, as you guessed, I did
end up paying a decent amount for it all, I'm bringing the car back in
for a third time to hopefully get it completely fixed. I will demand
to see the results of the vacuum test to make sure there are no leaks,
and also make sure their charge is adequate.
Hopefully this debacle will finally end. Thanks again.
Joe

Re: TJ A/C Issues
 

On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
> Joe writes:
> > Does anyone on here have any suggestions on other things to check?
>
> You may have an incompetent repairman. Ice anywhere on an A/C system is
> solid evidence of malfunction.
>
> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>
> A refrigerant undercharge is (paradoxically) one cause of icing. An
> undercharge will also behave as you describe, working OK in light loads,
> but not keeping up with more heat and/or humidity. So will a
> restriction in the system.
>
> Why was the low-pressure switch replaced? More guessing at your
> expense?
>
> When you have the evaporator and accumulator replaced, you should have
> demanded a vacuum leak test, where you actually personally get to watch
> the gages and see them hold a vacuum. So many A/C techs are incompetent
> or will wave off a slow leak because they make believe it is fixed or
> won't matter.
>
> If you've paid as much as I think you have for this work, then you
> should have been shown performance test results per the service manual.
> None of this wave-of-the-hand-your-done.
>
> A/C work is absolutely the worst to hire out. Huge prices for guys who
> pretend to know something they don't. That's why I learned to do it all
> myself.

First, thanks for the rapid reply. All of those repairs were done in
one fell swoop as a comprehensive repair to stop the system from
freezing up, and subsequently, restricting air flow through the vents,
especially after being at highway speeds for more than a few minutes.
This shop has always been competent in other repairs, but this A/C is
seemingly giving them a lot of trouble. Since, as you guessed, I did
end up paying a decent amount for it all, I'm bringing the car back in
for a third time to hopefully get it completely fixed. I will demand
to see the results of the vacuum test to make sure there are no leaks,
and also make sure their charge is adequate.
Hopefully this debacle will finally end. Thanks again.
Joe

Re: TJ A/C Issues
 

On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
> Joe writes:
> > Does anyone on here have any suggestions on other things to check?
>
> You may have an incompetent repairman. Ice anywhere on an A/C system is
> solid evidence of malfunction.
>
> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>
> A refrigerant undercharge is (paradoxically) one cause of icing. An
> undercharge will also behave as you describe, working OK in light loads,
> but not keeping up with more heat and/or humidity. So will a
> restriction in the system.
>
> Why was the low-pressure switch replaced? More guessing at your
> expense?
>
> When you have the evaporator and accumulator replaced, you should have
> demanded a vacuum leak test, where you actually personally get to watch
> the gages and see them hold a vacuum. So many A/C techs are incompetent
> or will wave off a slow leak because they make believe it is fixed or
> won't matter.
>
> If you've paid as much as I think you have for this work, then you
> should have been shown performance test results per the service manual.
> None of this wave-of-the-hand-your-done.
>
> A/C work is absolutely the worst to hire out. Huge prices for guys who
> pretend to know something they don't. That's why I learned to do it all
> myself.

First, thanks for the rapid reply. All of those repairs were done in
one fell swoop as a comprehensive repair to stop the system from
freezing up, and subsequently, restricting air flow through the vents,
especially after being at highway speeds for more than a few minutes.
This shop has always been competent in other repairs, but this A/C is
seemingly giving them a lot of trouble. Since, as you guessed, I did
end up paying a decent amount for it all, I'm bringing the car back in
for a third time to hopefully get it completely fixed. I will demand
to see the results of the vacuum test to make sure there are no leaks,
and also make sure their charge is adequate.
Hopefully this debacle will finally end. Thanks again.
Joe

Re: TJ A/C Issues
 

On Sat, 16 Jun 2007 06:48:30 -0700, Joe <UMparrothead@gmail.com>
wrote:

>On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
>> Joe writes:
>> > Does anyone on here have any suggestions on other things to check?
>>
>> You may have an incompetent repairman. Ice anywhere on an A/C system is
>> solid evidence of malfunction.
>>
>> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>>
>> A refrigerant undercharge is (paradoxically) one cause of icing. An
>> undercharge will also behave as you describe, working OK in light loads,
>> but not keeping up with more heat and/or humidity. So will a
>> restriction in the system.
>>
>> Why was the low-pressure switch replaced? More guessing at your
>> expense?
>>
>> When you have the evaporator and accumulator replaced, you should have
>> demanded a vacuum leak test, where you actually personally get to watch
>> the gages and see them hold a vacuum. So many A/C techs are incompetent
>> or will wave off a slow leak because they make believe it is fixed or
>> won't matter.
>>
>> If you've paid as much as I think you have for this work, then you
>> should have been shown performance test results per the service manual.
>> None of this wave-of-the-hand-your-done.
>>
>> A/C work is absolutely the worst to hire out. Huge prices for guys who
>> pretend to know something they don't. That's why I learned to do it all
>> myself.
>
>First, thanks for the rapid reply. All of those repairs were done in
>one fell swoop as a comprehensive repair to stop the system from
>freezing up, and subsequently, restricting air flow through the vents,
>especially after being at highway speeds for more than a few minutes.
>This shop has always been competent in other repairs, but this A/C is
>seemingly giving them a lot of trouble. Since, as you guessed, I did
>end up paying a decent amount for it all, I'm bringing the car back in
>for a third time to hopefully get it completely fixed. I will demand
>to see the results of the vacuum test to make sure there are no leaks,
>and also make sure their charge is adequate.
>Hopefully this debacle will finally end. Thanks again.
>Joe

Should have had a comprehensive diagnosis before the comprehensive
repair.

Sounds like a WAG to me.

Re: TJ A/C Issues
 

On Sat, 16 Jun 2007 06:48:30 -0700, Joe <UMparrothead@gmail.com>
wrote:

>On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
>> Joe writes:
>> > Does anyone on here have any suggestions on other things to check?
>>
>> You may have an incompetent repairman. Ice anywhere on an A/C system is
>> solid evidence of malfunction.
>>
>> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>>
>> A refrigerant undercharge is (paradoxically) one cause of icing. An
>> undercharge will also behave as you describe, working OK in light loads,
>> but not keeping up with more heat and/or humidity. So will a
>> restriction in the system.
>>
>> Why was the low-pressure switch replaced? More guessing at your
>> expense?
>>
>> When you have the evaporator and accumulator replaced, you should have
>> demanded a vacuum leak test, where you actually personally get to watch
>> the gages and see them hold a vacuum. So many A/C techs are incompetent
>> or will wave off a slow leak because they make believe it is fixed or
>> won't matter.
>>
>> If you've paid as much as I think you have for this work, then you
>> should have been shown performance test results per the service manual.
>> None of this wave-of-the-hand-your-done.
>>
>> A/C work is absolutely the worst to hire out. Huge prices for guys who
>> pretend to know something they don't. That's why I learned to do it all
>> myself.
>
>First, thanks for the rapid reply. All of those repairs were done in
>one fell swoop as a comprehensive repair to stop the system from
>freezing up, and subsequently, restricting air flow through the vents,
>especially after being at highway speeds for more than a few minutes.
>This shop has always been competent in other repairs, but this A/C is
>seemingly giving them a lot of trouble. Since, as you guessed, I did
>end up paying a decent amount for it all, I'm bringing the car back in
>for a third time to hopefully get it completely fixed. I will demand
>to see the results of the vacuum test to make sure there are no leaks,
>and also make sure their charge is adequate.
>Hopefully this debacle will finally end. Thanks again.
>Joe

Should have had a comprehensive diagnosis before the comprehensive
repair.

Sounds like a WAG to me.

Re: TJ A/C Issues
 

On Sat, 16 Jun 2007 06:48:30 -0700, Joe <UMparrothead@gmail.com>
wrote:

>On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
>> Joe writes:
>> > Does anyone on here have any suggestions on other things to check?
>>
>> You may have an incompetent repairman. Ice anywhere on an A/C system is
>> solid evidence of malfunction.
>>
>> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>>
>> A refrigerant undercharge is (paradoxically) one cause of icing. An
>> undercharge will also behave as you describe, working OK in light loads,
>> but not keeping up with more heat and/or humidity. So will a
>> restriction in the system.
>>
>> Why was the low-pressure switch replaced? More guessing at your
>> expense?
>>
>> When you have the evaporator and accumulator replaced, you should have
>> demanded a vacuum leak test, where you actually personally get to watch
>> the gages and see them hold a vacuum. So many A/C techs are incompetent
>> or will wave off a slow leak because they make believe it is fixed or
>> won't matter.
>>
>> If you've paid as much as I think you have for this work, then you
>> should have been shown performance test results per the service manual.
>> None of this wave-of-the-hand-your-done.
>>
>> A/C work is absolutely the worst to hire out. Huge prices for guys who
>> pretend to know something they don't. That's why I learned to do it all
>> myself.
>
>First, thanks for the rapid reply. All of those repairs were done in
>one fell swoop as a comprehensive repair to stop the system from
>freezing up, and subsequently, restricting air flow through the vents,
>especially after being at highway speeds for more than a few minutes.
>This shop has always been competent in other repairs, but this A/C is
>seemingly giving them a lot of trouble. Since, as you guessed, I did
>end up paying a decent amount for it all, I'm bringing the car back in
>for a third time to hopefully get it completely fixed. I will demand
>to see the results of the vacuum test to make sure there are no leaks,
>and also make sure their charge is adequate.
>Hopefully this debacle will finally end. Thanks again.
>Joe

Should have had a comprehensive diagnosis before the comprehensive
repair.

Sounds like a WAG to me.

Re: TJ A/C Issues
 

On Sat, 16 Jun 2007 06:48:30 -0700, Joe <UMparrothead@gmail.com>
wrote:

>On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
>> Joe writes:
>> > Does anyone on here have any suggestions on other things to check?
>>
>> You may have an incompetent repairman. Ice anywhere on an A/C system is
>> solid evidence of malfunction.
>>
>> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>>
>> A refrigerant undercharge is (paradoxically) one cause of icing. An
>> undercharge will also behave as you describe, working OK in light loads,
>> but not keeping up with more heat and/or humidity. So will a
>> restriction in the system.
>>
>> Why was the low-pressure switch replaced? More guessing at your
>> expense?
>>
>> When you have the evaporator and accumulator replaced, you should have
>> demanded a vacuum leak test, where you actually personally get to watch
>> the gages and see them hold a vacuum. So many A/C techs are incompetent
>> or will wave off a slow leak because they make believe it is fixed or
>> won't matter.
>>
>> If you've paid as much as I think you have for this work, then you
>> should have been shown performance test results per the service manual.
>> None of this wave-of-the-hand-your-done.
>>
>> A/C work is absolutely the worst to hire out. Huge prices for guys who
>> pretend to know something they don't. That's why I learned to do it all
>> myself.
>
>First, thanks for the rapid reply. All of those repairs were done in
>one fell swoop as a comprehensive repair to stop the system from
>freezing up, and subsequently, restricting air flow through the vents,
>especially after being at highway speeds for more than a few minutes.
>This shop has always been competent in other repairs, but this A/C is
>seemingly giving them a lot of trouble. Since, as you guessed, I did
>end up paying a decent amount for it all, I'm bringing the car back in
>for a third time to hopefully get it completely fixed. I will demand
>to see the results of the vacuum test to make sure there are no leaks,
>and also make sure their charge is adequate.
>Hopefully this debacle will finally end. Thanks again.
>Joe

Should have had a comprehensive diagnosis before the comprehensive
repair.

Sounds like a WAG to me.

Re: TJ A/C Issues
 

bllsht writes:

> Should have had a comprehensive diagnosis before the comprehensive
> repair.

Quite true. Even a truism. But how often wishful-thinking replaces solid
diagnosis.

Re: TJ A/C Issues
 

bllsht writes:

> Should have had a comprehensive diagnosis before the comprehensive
> repair.

Quite true. Even a truism. But how often wishful-thinking replaces solid
diagnosis.

Re: TJ A/C Issues
 

bllsht writes:

> Should have had a comprehensive diagnosis before the comprehensive
> repair.

Quite true. Even a truism. But how often wishful-thinking replaces solid
diagnosis.

Re: TJ A/C Issues
 

bllsht writes:

> Should have had a comprehensive diagnosis before the comprehensive
> repair.

Quite true. Even a truism. But how often wishful-thinking replaces solid
diagnosis.

Re: TJ A/C Issues
 

On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
> Joe writes:
> > Does anyone on here have any suggestions on other things to check?
>
> You may have an incompetent repairman. Ice anywhere on an A/C system is
> solid evidence of malfunction.
>
> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>
> A refrigerant undercharge is (paradoxically) one cause of icing. An
> undercharge will also behave as you describe, working OK in light loads,
> but not keeping up with more heat and/or humidity. So will a
> restriction in the system.
>
> Why was the low-pressure switch replaced? More guessing at your
> expense?
>
> When you have the evaporator and accumulator replaced, you should have
> demanded a vacuum leak test, where you actually personally get to watch
> the gages and see them hold a vacuum. So many A/C techs are incompetent
> or will wave off a slow leak because they make believe it is fixed or
> won't matter.
>
> If you've paid as much as I think you have for this work, then you
> should have been shown performance test results per the service manual.
> None of this wave-of-the-hand-your-done.
>
> A/C work is absolutely the worst to hire out. Huge prices for guys who
> pretend to know something they don't. That's why I learned to do it all
> myself.

Just curious, could any of those replaced components (evaporator,
accumulator, etc.) been damaged by a chronic undercharge of the system
(excessive and constant freezing up of system for probably 2 years)?
I try to keep my car in nearly perfect condition, and this issue was
misdiagnosed so many times that it persisted as the freezing problem
continued for quite a while. I just want to make sure those parts
were not compromised *because* the shop dismissed the problems for so
long, in which case, making the responsible for their failure. Thanks
again.
Joe

Re: TJ A/C Issues
 

On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
> Joe writes:
> > Does anyone on here have any suggestions on other things to check?
>
> You may have an incompetent repairman. Ice anywhere on an A/C system is
> solid evidence of malfunction.
>
> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>
> A refrigerant undercharge is (paradoxically) one cause of icing. An
> undercharge will also behave as you describe, working OK in light loads,
> but not keeping up with more heat and/or humidity. So will a
> restriction in the system.
>
> Why was the low-pressure switch replaced? More guessing at your
> expense?
>
> When you have the evaporator and accumulator replaced, you should have
> demanded a vacuum leak test, where you actually personally get to watch
> the gages and see them hold a vacuum. So many A/C techs are incompetent
> or will wave off a slow leak because they make believe it is fixed or
> won't matter.
>
> If you've paid as much as I think you have for this work, then you
> should have been shown performance test results per the service manual.
> None of this wave-of-the-hand-your-done.
>
> A/C work is absolutely the worst to hire out. Huge prices for guys who
> pretend to know something they don't. That's why I learned to do it all
> myself.

Just curious, could any of those replaced components (evaporator,
accumulator, etc.) been damaged by a chronic undercharge of the system
(excessive and constant freezing up of system for probably 2 years)?
I try to keep my car in nearly perfect condition, and this issue was
misdiagnosed so many times that it persisted as the freezing problem
continued for quite a while. I just want to make sure those parts
were not compromised *because* the shop dismissed the problems for so
long, in which case, making the responsible for their failure. Thanks
again.
Joe

Re: TJ A/C Issues
 

On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
> Joe writes:
> > Does anyone on here have any suggestions on other things to check?
>
> You may have an incompetent repairman. Ice anywhere on an A/C system is
> solid evidence of malfunction.
>
> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>
> A refrigerant undercharge is (paradoxically) one cause of icing. An
> undercharge will also behave as you describe, working OK in light loads,
> but not keeping up with more heat and/or humidity. So will a
> restriction in the system.
>
> Why was the low-pressure switch replaced? More guessing at your
> expense?
>
> When you have the evaporator and accumulator replaced, you should have
> demanded a vacuum leak test, where you actually personally get to watch
> the gages and see them hold a vacuum. So many A/C techs are incompetent
> or will wave off a slow leak because they make believe it is fixed or
> won't matter.
>
> If you've paid as much as I think you have for this work, then you
> should have been shown performance test results per the service manual.
> None of this wave-of-the-hand-your-done.
>
> A/C work is absolutely the worst to hire out. Huge prices for guys who
> pretend to know something they don't. That's why I learned to do it all
> myself.

Just curious, could any of those replaced components (evaporator,
accumulator, etc.) been damaged by a chronic undercharge of the system
(excessive and constant freezing up of system for probably 2 years)?
I try to keep my car in nearly perfect condition, and this issue was
misdiagnosed so many times that it persisted as the freezing problem
continued for quite a while. I just want to make sure those parts
were not compromised *because* the shop dismissed the problems for so
long, in which case, making the responsible for their failure. Thanks
again.
Joe

Re: TJ A/C Issues
 

On Jun 16, 12:38 am, Richard J Kinch <k...@truetex.com> wrote:
> Joe writes:
> > Does anyone on here have any suggestions on other things to check?
>
> You may have an incompetent repairman. Ice anywhere on an A/C system is
> solid evidence of malfunction.
>
> Replacing hoses to fix icing?!?!?! Who swindled you on that?
>
> A refrigerant undercharge is (paradoxically) one cause of icing. An
> undercharge will also behave as you describe, working OK in light loads,
> but not keeping up with more heat and/or humidity. So will a
> restriction in the system.
>
> Why was the low-pressure switch replaced? More guessing at your
> expense?
>
> When you have the evaporator and accumulator replaced, you should have
> demanded a vacuum leak test, where you actually personally get to watch
> the gages and see them hold a vacuum. So many A/C techs are incompetent
> or will wave off a slow leak because they make believe it is fixed or
> won't matter.
>
> If you've paid as much as I think you have for this work, then you
> should have been shown performance test results per the service manual.
> None of this wave-of-the-hand-your-done.
>
> A/C work is absolutely the worst to hire out. Huge prices for guys who
> pretend to know something they don't. That's why I learned to do it all
> myself.

Just curious, could any of those replaced components (evaporator,
accumulator, etc.) been damaged by a chronic undercharge of the system
(excessive and constant freezing up of system for probably 2 years)?
I try to keep my car in nearly perfect condition, and this issue was
misdiagnosed so many times that it persisted as the freezing problem
continued for quite a while. I just want to make sure those parts
were not compromised *because* the shop dismissed the problems for so
long, in which case, making the responsible for their failure. Thanks
again.
Joe

Re: TJ A/C Issues
 

On Sat, 16 Jun 2007 03:07:44 -0000, Joe <UMparrothead@gmail.com>
wrote:

>Does anyone on here have any suggestions on other things to check?
>Since the summer is in full swing, I'd really like to get this A/C
>problem finally fixed. Thanks for anything you've got.


One thing that can help A/C output overall is to shutoff water flow to
heater core in summer (Lowes sells some in line ball valves that do
nicely when adapted to this here) The reason for this is not most car
simply try to route air around heater core in hot weather but the 200
plus cores is still in there on a hot day radiating heat into ducts.
This is why when you shut your car off on a hot day for a while and
then start it up it blows hot air for a while from A/C vents because
the hot core heat soaks the whole A/C and heater box when you shut it
down. I have done this to all my SUV's. It helps the air be a bit
cold overall as well because the ducts doors and such leak with age
and shutting off the hot water cures this leakage for good. You will
notice first time you hot start it after it sits for a bit that there
will be no blast of hot air from vents for heater core cooking ducts
and A/C will work better in recirculate mode too because there will be
no hot spots in the ductwork to warm air and full capacity will go to
cooling car. I can run my truck in 90 plus weather, blowing snow
flakes so to speak, stop for a while and then start it back up and no
heat soaked blast and have full cooling in a matter of seconds. You
may have some other issues but it kinda sounds to me the you may have
some heater door leakage and heat soak because the hotter it gets the
hotter the coolant is going to tend to get and the more it is going to
warm your air in ducts. Long ago they used to shut water flow off on a
lot of vehcile when heat was not on and A/C was selected but to save
prodcution costs they did away with that long ago. (back in 1990 GM
even issued a service bulletin for 89 burbs like mine that added a
water cutoff valve to heater core curcuit during A/C max operation
because of door/baffle leakage on some models.
-----------------
TheSnoMan.com

Re: TJ A/C Issues
 

On Sat, 16 Jun 2007 03:07:44 -0000, Joe <UMparrothead@gmail.com>
wrote:

>Does anyone on here have any suggestions on other things to check?
>Since the summer is in full swing, I'd really like to get this A/C
>problem finally fixed. Thanks for anything you've got.


One thing that can help A/C output overall is to shutoff water flow to
heater core in summer (Lowes sells some in line ball valves that do
nicely when adapted to this here) The reason for this is not most car
simply try to route air around heater core in hot weather but the 200
plus cores is still in there on a hot day radiating heat into ducts.
This is why when you shut your car off on a hot day for a while and
then start it up it blows hot air for a while from A/C vents because
the hot core heat soaks the whole A/C and heater box when you shut it
down. I have done this to all my SUV's. It helps the air be a bit
cold overall as well because the ducts doors and such leak with age
and shutting off the hot water cures this leakage for good. You will
notice first time you hot start it after it sits for a bit that there
will be no blast of hot air from vents for heater core cooking ducts
and A/C will work better in recirculate mode too because there will be
no hot spots in the ductwork to warm air and full capacity will go to
cooling car. I can run my truck in 90 plus weather, blowing snow
flakes so to speak, stop for a while and then start it back up and no
heat soaked blast and have full cooling in a matter of seconds. You
may have some other issues but it kinda sounds to me the you may have
some heater door leakage and heat soak because the hotter it gets the
hotter the coolant is going to tend to get and the more it is going to
warm your air in ducts. Long ago they used to shut water flow off on a
lot of vehcile when heat was not on and A/C was selected but to save
prodcution costs they did away with that long ago. (back in 1990 GM
even issued a service bulletin for 89 burbs like mine that added a
water cutoff valve to heater core curcuit during A/C max operation
because of door/baffle leakage on some models.
-----------------
TheSnoMan.com

Re: TJ A/C Issues
 

On Sat, 16 Jun 2007 03:07:44 -0000, Joe <UMparrothead@gmail.com>
wrote:

>Does anyone on here have any suggestions on other things to check?
>Since the summer is in full swing, I'd really like to get this A/C
>problem finally fixed. Thanks for anything you've got.


One thing that can help A/C output overall is to shutoff water flow to
heater core in summer (Lowes sells some in line ball valves that do
nicely when adapted to this here) The reason for this is not most car
simply try to route air around heater core in hot weather but the 200
plus cores is still in there on a hot day radiating heat into ducts.
This is why when you shut your car off on a hot day for a while and
then start it up it blows hot air for a while from A/C vents because
the hot core heat soaks the whole A/C and heater box when you shut it
down. I have done this to all my SUV's. It helps the air be a bit
cold overall as well because the ducts doors and such leak with age
and shutting off the hot water cures this leakage for good. You will
notice first time you hot start it after it sits for a bit that there
will be no blast of hot air from vents for heater core cooking ducts
and A/C will work better in recirculate mode too because there will be
no hot spots in the ductwork to warm air and full capacity will go to
cooling car. I can run my truck in 90 plus weather, blowing snow
flakes so to speak, stop for a while and then start it back up and no
heat soaked blast and have full cooling in a matter of seconds. You
may have some other issues but it kinda sounds to me the you may have
some heater door leakage and heat soak because the hotter it gets the
hotter the coolant is going to tend to get and the more it is going to
warm your air in ducts. Long ago they used to shut water flow off on a
lot of vehcile when heat was not on and A/C was selected but to save
prodcution costs they did away with that long ago. (back in 1990 GM
even issued a service bulletin for 89 burbs like mine that added a
water cutoff valve to heater core curcuit during A/C max operation
because of door/baffle leakage on some models.
-----------------
TheSnoMan.com

Re: TJ A/C Issues
 

On Sat, 16 Jun 2007 03:07:44 -0000, Joe <UMparrothead@gmail.com>
wrote:

>Does anyone on here have any suggestions on other things to check?
>Since the summer is in full swing, I'd really like to get this A/C
>problem finally fixed. Thanks for anything you've got.


One thing that can help A/C output overall is to shutoff water flow to
heater core in summer (Lowes sells some in line ball valves that do
nicely when adapted to this here) The reason for this is not most car
simply try to route air around heater core in hot weather but the 200
plus cores is still in there on a hot day radiating heat into ducts.
This is why when you shut your car off on a hot day for a while and
then start it up it blows hot air for a while from A/C vents because
the hot core heat soaks the whole A/C and heater box when you shut it
down. I have done this to all my SUV's. It helps the air be a bit
cold overall as well because the ducts doors and such leak with age
and shutting off the hot water cures this leakage for good. You will
notice first time you hot start it after it sits for a bit that there
will be no blast of hot air from vents for heater core cooking ducts
and A/C will work better in recirculate mode too because there will be
no hot spots in the ductwork to warm air and full capacity will go to
cooling car. I can run my truck in 90 plus weather, blowing snow
flakes so to speak, stop for a while and then start it back up and no
heat soaked blast and have full cooling in a matter of seconds. You
may have some other issues but it kinda sounds to me the you may have
some heater door leakage and heat soak because the hotter it gets the
hotter the coolant is going to tend to get and the more it is going to
warm your air in ducts. Long ago they used to shut water flow off on a
lot of vehcile when heat was not on and A/C was selected but to save
prodcution costs they did away with that long ago. (back in 1990 GM
even issued a service bulletin for 89 burbs like mine that added a
water cutoff valve to heater core curcuit during A/C max operation
because of door/baffle leakage on some models.
-----------------
TheSnoMan.com

Re: TJ A/C Issues
 

Joe writes:

> Just curious, could any of those replaced components (evaporator,
> accumulator, etc.) been damaged by a chronic undercharge of the system
> (excessive and constant freezing up of system for probably 2 years)?

Not likely.

With undercharge you can get below atmospheric pressure conditions in the
system which pulls in (moist) ambient air if there are leaks. The
accumulator contains a dessicant packet to absorb any moisture. The
dessicant can be saturated if enough moisture is introduced, but that's
quite a lot.

Freezing doesn't usually cause ice-expansion damage, if that's what you're
worried about, since the ice is typically building up from sublimated water
vapor, not liquid water. This is how your household "frost free"
refrigerator-freezer works, building up frost on the evaporator which must
be defrosted with an automatic heating cycle once or twice a day.

Re: TJ A/C Issues
 

Joe writes:

> Just curious, could any of those replaced components (evaporator,
> accumulator, etc.) been damaged by a chronic undercharge of the system
> (excessive and constant freezing up of system for probably 2 years)?

Not likely.

With undercharge you can get below atmospheric pressure conditions in the
system which pulls in (moist) ambient air if there are leaks. The
accumulator contains a dessicant packet to absorb any moisture. The
dessicant can be saturated if enough moisture is introduced, but that's
quite a lot.

Freezing doesn't usually cause ice-expansion damage, if that's what you're
worried about, since the ice is typically building up from sublimated water
vapor, not liquid water. This is how your household "frost free"
refrigerator-freezer works, building up frost on the evaporator which must
be defrosted with an automatic heating cycle once or twice a day.

Re: TJ A/C Issues
 

Joe writes:

> Just curious, could any of those replaced components (evaporator,
> accumulator, etc.) been damaged by a chronic undercharge of the system
> (excessive and constant freezing up of system for probably 2 years)?

Not likely.

With undercharge you can get below atmospheric pressure conditions in the
system which pulls in (moist) ambient air if there are leaks. The
accumulator contains a dessicant packet to absorb any moisture. The
dessicant can be saturated if enough moisture is introduced, but that's
quite a lot.

Freezing doesn't usually cause ice-expansion damage, if that's what you're
worried about, since the ice is typically building up from sublimated water
vapor, not liquid water. This is how your household "frost free"
refrigerator-freezer works, building up frost on the evaporator which must
be defrosted with an automatic heating cycle once or twice a day.

Re: TJ A/C Issues
 

Joe writes:

> Just curious, could any of those replaced components (evaporator,
> accumulator, etc.) been damaged by a chronic undercharge of the system
> (excessive and constant freezing up of system for probably 2 years)?

Not likely.

With undercharge you can get below atmospheric pressure conditions in the
system which pulls in (moist) ambient air if there are leaks. The
accumulator contains a dessicant packet to absorb any moisture. The
dessicant can be saturated if enough moisture is introduced, but that's
quite a lot.

Freezing doesn't usually cause ice-expansion damage, if that's what you're
worried about, since the ice is typically building up from sublimated water
vapor, not liquid water. This is how your household "frost free"
refrigerator-freezer works, building up frost on the evaporator which must
be defrosted with an automatic heating cycle once or twice a day.

Re: Re: TJ A/C Issues
 

On Mon, 18 Jun 2007 14:51:49 -0500, Richard J Kinch
<kinch@truetex.com> wrote:

>With undercharge you can get below atmospheric pressure conditions in the
>system which pulls in (moist) ambient air if there are leaks. The
>accumulator contains a dessicant packet to absorb any moisture. The
>dessicant can be saturated if enough moisture is introduced, but that's
>quite a lot.


Never happen, the low pressure cutout switch would kick in long before
you even came close to negative pressure. It could MAYBE happen in
theory if you had a very very low charge and a bypassed low pressure
switch but even then the expansion orifice would limit the pressure
differentail and keep it from going very far negative and also pump
would sieze soon to because with not refrigerant curculating their
would be no lube for compressor (this is one reason for low pressure
cutout switch)
-----------------
TheSnoMan.com

Re: Re: TJ A/C Issues
 

On Mon, 18 Jun 2007 14:51:49 -0500, Richard J Kinch
<kinch@truetex.com> wrote:

>With undercharge you can get below atmospheric pressure conditions in the
>system which pulls in (moist) ambient air if there are leaks. The
>accumulator contains a dessicant packet to absorb any moisture. The
>dessicant can be saturated if enough moisture is introduced, but that's
>quite a lot.


Never happen, the low pressure cutout switch would kick in long before
you even came close to negative pressure. It could MAYBE happen in
theory if you had a very very low charge and a bypassed low pressure
switch but even then the expansion orifice would limit the pressure
differentail and keep it from going very far negative and also pump
would sieze soon to because with not refrigerant curculating their
would be no lube for compressor (this is one reason for low pressure
cutout switch)
-----------------
TheSnoMan.com

Re: Re: TJ A/C Issues
 

On Mon, 18 Jun 2007 14:51:49 -0500, Richard J Kinch
<kinch@truetex.com> wrote:

>With undercharge you can get below atmospheric pressure conditions in the
>system which pulls in (moist) ambient air if there are leaks. The
>accumulator contains a dessicant packet to absorb any moisture. The
>dessicant can be saturated if enough moisture is introduced, but that's
>quite a lot.


Never happen, the low pressure cutout switch would kick in long before
you even came close to negative pressure. It could MAYBE happen in
theory if you had a very very low charge and a bypassed low pressure
switch but even then the expansion orifice would limit the pressure
differentail and keep it from going very far negative and also pump
would sieze soon to because with not refrigerant curculating their
would be no lube for compressor (this is one reason for low pressure
cutout switch)
-----------------
TheSnoMan.com

Re: Re: TJ A/C Issues
 

On Mon, 18 Jun 2007 14:51:49 -0500, Richard J Kinch
<kinch@truetex.com> wrote:

>With undercharge you can get below atmospheric pressure conditions in the
>system which pulls in (moist) ambient air if there are leaks. The
>accumulator contains a dessicant packet to absorb any moisture. The
>dessicant can be saturated if enough moisture is introduced, but that's
>quite a lot.


Never happen, the low pressure cutout switch would kick in long before
you even came close to negative pressure. It could MAYBE happen in
theory if you had a very very low charge and a bypassed low pressure
switch but even then the expansion orifice would limit the pressure
differentail and keep it from going very far negative and also pump
would sieze soon to because with not refrigerant curculating their
would be no lube for compressor (this is one reason for low pressure
cutout switch)
-----------------
TheSnoMan.com

Re: TJ A/C Issues
 

On Jun 18, 7:27 pm, SnoMan <a...@snoman.com> wrote:
> On Mon, 18 Jun 2007 14:51:49 -0500, Richard J Kinch
>
> <k...@truetex.com> wrote:
> >With undercharge you can get below atmospheric pressure conditions in the
> >system which pulls in (moist) ambient air if there are leaks. The
> >accumulator contains a dessicant packet to absorb any moisture. The
> >dessicant can be saturated if enough moisture is introduced, but that's
> >quite a lot.
>
> Never happen, the low pressure cutout switch would kick in long before
> you even came close to negative pressure. It could MAYBE happen in
> theory if you had a very very low charge and a bypassed low pressure
> switch but even then the expansion orifice would limit the pressure
> differentail and keep it from going very far negative and also pump
> would sieze soon to because with not refrigerant curculating their
> would be no lube for compressor (this is one reason for low pressure
> cutout switch)
> -----------------
> TheSnoMan.com

Just got the car back, turns out the initial evaporator leakage
damaged the compressor and it could no longer maintain a low-enough
pressure to cool on hot/humid days. At about 75-80 degrees ambient,
it could only reach 60 psi at the low end, when it is supposed to get
down to about 20 psi. A pressure test was performed before repairs
and it showed no leakage, refrigerant was at top levels. Verified a
vacuum test with 0 leakage for 7 minutes after replacing the
compressor. Current air output at any fan speed is 32 degrees and
compressor now cycles, which it hadn't done for years before.
Hopefully it is done for a long time, and I appreciate the assistance,
as well as the suggestion for the bypass to the heater core - I'll
look into that for my car.
Joe

Re: TJ A/C Issues
 

On Jun 18, 7:27 pm, SnoMan <a...@snoman.com> wrote:
> On Mon, 18 Jun 2007 14:51:49 -0500, Richard J Kinch
>
> <k...@truetex.com> wrote:
> >With undercharge you can get below atmospheric pressure conditions in the
> >system which pulls in (moist) ambient air if there are leaks. The
> >accumulator contains a dessicant packet to absorb any moisture. The
> >dessicant can be saturated if enough moisture is introduced, but that's
> >quite a lot.
>
> Never happen, the low pressure cutout switch would kick in long before
> you even came close to negative pressure. It could MAYBE happen in
> theory if you had a very very low charge and a bypassed low pressure
> switch but even then the expansion orifice would limit the pressure
> differentail and keep it from going very far negative and also pump
> would sieze soon to because with not refrigerant curculating their
> would be no lube for compressor (this is one reason for low pressure
> cutout switch)
> -----------------
> TheSnoMan.com

Just got the car back, turns out the initial evaporator leakage
damaged the compressor and it could no longer maintain a low-enough
pressure to cool on hot/humid days. At about 75-80 degrees ambient,
it could only reach 60 psi at the low end, when it is supposed to get
down to about 20 psi. A pressure test was performed before repairs
and it showed no leakage, refrigerant was at top levels. Verified a
vacuum test with 0 leakage for 7 minutes after replacing the
compressor. Current air output at any fan speed is 32 degrees and
compressor now cycles, which it hadn't done for years before.
Hopefully it is done for a long time, and I appreciate the assistance,
as well as the suggestion for the bypass to the heater core - I'll
look into that for my car.
Joe

Re: TJ A/C Issues
 

On Jun 18, 7:27 pm, SnoMan <a...@snoman.com> wrote:
> On Mon, 18 Jun 2007 14:51:49 -0500, Richard J Kinch
>
> <k...@truetex.com> wrote:
> >With undercharge you can get below atmospheric pressure conditions in the
> >system which pulls in (moist) ambient air if there are leaks. The
> >accumulator contains a dessicant packet to absorb any moisture. The
> >dessicant can be saturated if enough moisture is introduced, but that's
> >quite a lot.
>
> Never happen, the low pressure cutout switch would kick in long before
> you even came close to negative pressure. It could MAYBE happen in
> theory if you had a very very low charge and a bypassed low pressure
> switch but even then the expansion orifice would limit the pressure
> differentail and keep it from going very far negative and also pump
> would sieze soon to because with not refrigerant curculating their
> would be no lube for compressor (this is one reason for low pressure
> cutout switch)
> -----------------
> TheSnoMan.com

Just got the car back, turns out the initial evaporator leakage
damaged the compressor and it could no longer maintain a low-enough
pressure to cool on hot/humid days. At about 75-80 degrees ambient,
it could only reach 60 psi at the low end, when it is supposed to get
down to about 20 psi. A pressure test was performed before repairs
and it showed no leakage, refrigerant was at top levels. Verified a
vacuum test with 0 leakage for 7 minutes after replacing the
compressor. Current air output at any fan speed is 32 degrees and
compressor now cycles, which it hadn't done for years before.
Hopefully it is done for a long time, and I appreciate the assistance,
as well as the suggestion for the bypass to the heater core - I'll
look into that for my car.
Joe

Re: TJ A/C Issues
 

On Jun 18, 7:27 pm, SnoMan <a...@snoman.com> wrote:
> On Mon, 18 Jun 2007 14:51:49 -0500, Richard J Kinch
>
> <k...@truetex.com> wrote:
> >With undercharge you can get below atmospheric pressure conditions in the
> >system which pulls in (moist) ambient air if there are leaks. The
> >accumulator contains a dessicant packet to absorb any moisture. The
> >dessicant can be saturated if enough moisture is introduced, but that's
> >quite a lot.
>
> Never happen, the low pressure cutout switch would kick in long before
> you even came close to negative pressure. It could MAYBE happen in
> theory if you had a very very low charge and a bypassed low pressure
> switch but even then the expansion orifice would limit the pressure
> differentail and keep it from going very far negative and also pump
> would sieze soon to because with not refrigerant curculating their
> would be no lube for compressor (this is one reason for low pressure
> cutout switch)
> -----------------
> TheSnoMan.com

Just got the car back, turns out the initial evaporator leakage
damaged the compressor and it could no longer maintain a low-enough
pressure to cool on hot/humid days. At about 75-80 degrees ambient,
it could only reach 60 psi at the low end, when it is supposed to get
down to about 20 psi. A pressure test was performed before repairs
and it showed no leakage, refrigerant was at top levels. Verified a
vacuum test with 0 leakage for 7 minutes after replacing the
compressor. Current air output at any fan speed is 32 degrees and
compressor now cycles, which it hadn't done for years before.
Hopefully it is done for a long time, and I appreciate the assistance,
as well as the suggestion for the bypass to the heater core - I'll
look into that for my car.
Joe

Re: Re: TJ A/C Issues
 

SnoMan writes:

> Never happen, the low pressure cutout switch would kick in long before
> you even came close to negative pressure.

One would hope so, but the OP said that was faulty.

A leak means you have no pressure sooner or later with the system off.
If it is turned on and runs (faulty low-pressure switch), it will
certainly have negative pressure (vs ambient) on the suction side, and a
leak in that half will pull in air and moisture. Even without running,
a leaky system admits air and moisture slowly after the refrigerant is
gone. Consider that a system that fails due to a refrigerant leak will
often go for months or years before being repaired, so the dessicant
will be saturated, just due to amibent temperature and barometric
cycling.

A/C technicians often have a superstition that their vacuum pump removes
moisture from a contaminated system, including regenerating the
dessicant. Not true. You should replace the dessicant (which means the
whole accumulator on a TJ) if there's any chance it was open to the air,
leaky for a long time, or otherwise compromised.

If you want to regenerate dessicant, you have to bake it. Room
temperature vacuum is not enough.

Re: Re: TJ A/C Issues
 

SnoMan writes:

> Never happen, the low pressure cutout switch would kick in long before
> you even came close to negative pressure.

One would hope so, but the OP said that was faulty.

A leak means you have no pressure sooner or later with the system off.
If it is turned on and runs (faulty low-pressure switch), it will
certainly have negative pressure (vs ambient) on the suction side, and a
leak in that half will pull in air and moisture. Even without running,
a leaky system admits air and moisture slowly after the refrigerant is
gone. Consider that a system that fails due to a refrigerant leak will
often go for months or years before being repaired, so the dessicant
will be saturated, just due to amibent temperature and barometric
cycling.

A/C technicians often have a superstition that their vacuum pump removes
moisture from a contaminated system, including regenerating the
dessicant. Not true. You should replace the dessicant (which means the
whole accumulator on a TJ) if there's any chance it was open to the air,
leaky for a long time, or otherwise compromised.

If you want to regenerate dessicant, you have to bake it. Room
temperature vacuum is not enough.

Re: Re: TJ A/C Issues
 

SnoMan writes:

> Never happen, the low pressure cutout switch would kick in long before
> you even came close to negative pressure.

One would hope so, but the OP said that was faulty.

A leak means you have no pressure sooner or later with the system off.
If it is turned on and runs (faulty low-pressure switch), it will
certainly have negative pressure (vs ambient) on the suction side, and a
leak in that half will pull in air and moisture. Even without running,
a leaky system admits air and moisture slowly after the refrigerant is
gone. Consider that a system that fails due to a refrigerant leak will
often go for months or years before being repaired, so the dessicant
will be saturated, just due to amibent temperature and barometric
cycling.

A/C technicians often have a superstition that their vacuum pump removes
moisture from a contaminated system, including regenerating the
dessicant. Not true. You should replace the dessicant (which means the
whole accumulator on a TJ) if there's any chance it was open to the air,
leaky for a long time, or otherwise compromised.

If you want to regenerate dessicant, you have to bake it. Room
temperature vacuum is not enough.