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.