99 Cherokee HVAC Problem
#11
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
Your vacuum reservoir is collapsed, or there is a vacuum leak.
Earle
"JB" <janie557@hotmail.com> wrote in message
news:1153720065.401864.220210@i3g2000cwc.googlegro ups.com...
A recent 300 mile camping trip pulling a small tent trailer afforded an
opportunity to better characterize the problems with the HVAC of our
1999 Jeep Cherokee. We'd taken it in the week before our trip with a
complaint that the ventilation would randomly shut off the vents
although the fan continued to run. Our repair shop found a technical
service bulletin that was relevant, diagnosed a failing panel vacuum
actuator, and replaced the unit.
However, on our trip we had the same problem but now were able to
observe that the ventilation shuts down under conditions of high
manifold pressure (e.g., going up hill) but the ventilation was
restored on level or downhill grades. Rapid acceleration on level
ground also caused the ventilation to shutdown.
This behavior was consistent regardless of whether the air conditioner
was selected or just simple fresh air ventilation. We did not check
whether it occurred when the selector was positioned for defrost.
A possibly related problem is occurring with the "factory installed"
cruise control. It used to be quite solid, keeping the speed within ±
one mph--now it has a good five to ten mph slop and can take tens of
seconds to resume the set speed.
Fuel consumption has remained constant, we continue to get 20 mpg,
in-town and on the highway with or without the trailer. I have noticed
that the engine seems to have some hesitation and not quite the same
acceleration lately but it is approaching 90,000 and is time for
service.
Any help would be appreciated.
Janie
Earle
"JB" <janie557@hotmail.com> wrote in message
news:1153720065.401864.220210@i3g2000cwc.googlegro ups.com...
A recent 300 mile camping trip pulling a small tent trailer afforded an
opportunity to better characterize the problems with the HVAC of our
1999 Jeep Cherokee. We'd taken it in the week before our trip with a
complaint that the ventilation would randomly shut off the vents
although the fan continued to run. Our repair shop found a technical
service bulletin that was relevant, diagnosed a failing panel vacuum
actuator, and replaced the unit.
However, on our trip we had the same problem but now were able to
observe that the ventilation shuts down under conditions of high
manifold pressure (e.g., going up hill) but the ventilation was
restored on level or downhill grades. Rapid acceleration on level
ground also caused the ventilation to shutdown.
This behavior was consistent regardless of whether the air conditioner
was selected or just simple fresh air ventilation. We did not check
whether it occurred when the selector was positioned for defrost.
A possibly related problem is occurring with the "factory installed"
cruise control. It used to be quite solid, keeping the speed within ±
one mph--now it has a good five to ten mph slop and can take tens of
seconds to resume the set speed.
Fuel consumption has remained constant, we continue to get 20 mpg,
in-town and on the highway with or without the trailer. I have noticed
that the engine seems to have some hesitation and not quite the same
acceleration lately but it is approaching 90,000 and is time for
service.
Any help would be appreciated.
Janie
#12
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
Your vacuum reservoir is collapsed, or there is a vacuum leak.
Earle
"JB" <janie557@hotmail.com> wrote in message
news:1153720065.401864.220210@i3g2000cwc.googlegro ups.com...
A recent 300 mile camping trip pulling a small tent trailer afforded an
opportunity to better characterize the problems with the HVAC of our
1999 Jeep Cherokee. We'd taken it in the week before our trip with a
complaint that the ventilation would randomly shut off the vents
although the fan continued to run. Our repair shop found a technical
service bulletin that was relevant, diagnosed a failing panel vacuum
actuator, and replaced the unit.
However, on our trip we had the same problem but now were able to
observe that the ventilation shuts down under conditions of high
manifold pressure (e.g., going up hill) but the ventilation was
restored on level or downhill grades. Rapid acceleration on level
ground also caused the ventilation to shutdown.
This behavior was consistent regardless of whether the air conditioner
was selected or just simple fresh air ventilation. We did not check
whether it occurred when the selector was positioned for defrost.
A possibly related problem is occurring with the "factory installed"
cruise control. It used to be quite solid, keeping the speed within ±
one mph--now it has a good five to ten mph slop and can take tens of
seconds to resume the set speed.
Fuel consumption has remained constant, we continue to get 20 mpg,
in-town and on the highway with or without the trailer. I have noticed
that the engine seems to have some hesitation and not quite the same
acceleration lately but it is approaching 90,000 and is time for
service.
Any help would be appreciated.
Janie
Earle
"JB" <janie557@hotmail.com> wrote in message
news:1153720065.401864.220210@i3g2000cwc.googlegro ups.com...
A recent 300 mile camping trip pulling a small tent trailer afforded an
opportunity to better characterize the problems with the HVAC of our
1999 Jeep Cherokee. We'd taken it in the week before our trip with a
complaint that the ventilation would randomly shut off the vents
although the fan continued to run. Our repair shop found a technical
service bulletin that was relevant, diagnosed a failing panel vacuum
actuator, and replaced the unit.
However, on our trip we had the same problem but now were able to
observe that the ventilation shuts down under conditions of high
manifold pressure (e.g., going up hill) but the ventilation was
restored on level or downhill grades. Rapid acceleration on level
ground also caused the ventilation to shutdown.
This behavior was consistent regardless of whether the air conditioner
was selected or just simple fresh air ventilation. We did not check
whether it occurred when the selector was positioned for defrost.
A possibly related problem is occurring with the "factory installed"
cruise control. It used to be quite solid, keeping the speed within ±
one mph--now it has a good five to ten mph slop and can take tens of
seconds to resume the set speed.
Fuel consumption has remained constant, we continue to get 20 mpg,
in-town and on the highway with or without the trailer. I have noticed
that the engine seems to have some hesitation and not quite the same
acceleration lately but it is approaching 90,000 and is time for
service.
Any help would be appreciated.
Janie
#13
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
Your vacuum reservoir is collapsed, or there is a vacuum leak.
Earle
"JB" <janie557@hotmail.com> wrote in message
news:1153720065.401864.220210@i3g2000cwc.googlegro ups.com...
A recent 300 mile camping trip pulling a small tent trailer afforded an
opportunity to better characterize the problems with the HVAC of our
1999 Jeep Cherokee. We'd taken it in the week before our trip with a
complaint that the ventilation would randomly shut off the vents
although the fan continued to run. Our repair shop found a technical
service bulletin that was relevant, diagnosed a failing panel vacuum
actuator, and replaced the unit.
However, on our trip we had the same problem but now were able to
observe that the ventilation shuts down under conditions of high
manifold pressure (e.g., going up hill) but the ventilation was
restored on level or downhill grades. Rapid acceleration on level
ground also caused the ventilation to shutdown.
This behavior was consistent regardless of whether the air conditioner
was selected or just simple fresh air ventilation. We did not check
whether it occurred when the selector was positioned for defrost.
A possibly related problem is occurring with the "factory installed"
cruise control. It used to be quite solid, keeping the speed within ±
one mph--now it has a good five to ten mph slop and can take tens of
seconds to resume the set speed.
Fuel consumption has remained constant, we continue to get 20 mpg,
in-town and on the highway with or without the trailer. I have noticed
that the engine seems to have some hesitation and not quite the same
acceleration lately but it is approaching 90,000 and is time for
service.
Any help would be appreciated.
Janie
Earle
"JB" <janie557@hotmail.com> wrote in message
news:1153720065.401864.220210@i3g2000cwc.googlegro ups.com...
A recent 300 mile camping trip pulling a small tent trailer afforded an
opportunity to better characterize the problems with the HVAC of our
1999 Jeep Cherokee. We'd taken it in the week before our trip with a
complaint that the ventilation would randomly shut off the vents
although the fan continued to run. Our repair shop found a technical
service bulletin that was relevant, diagnosed a failing panel vacuum
actuator, and replaced the unit.
However, on our trip we had the same problem but now were able to
observe that the ventilation shuts down under conditions of high
manifold pressure (e.g., going up hill) but the ventilation was
restored on level or downhill grades. Rapid acceleration on level
ground also caused the ventilation to shutdown.
This behavior was consistent regardless of whether the air conditioner
was selected or just simple fresh air ventilation. We did not check
whether it occurred when the selector was positioned for defrost.
A possibly related problem is occurring with the "factory installed"
cruise control. It used to be quite solid, keeping the speed within ±
one mph--now it has a good five to ten mph slop and can take tens of
seconds to resume the set speed.
Fuel consumption has remained constant, we continue to get 20 mpg,
in-town and on the highway with or without the trailer. I have noticed
that the engine seems to have some hesitation and not quite the same
acceleration lately but it is approaching 90,000 and is time for
service.
Any help would be appreciated.
Janie
#14
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
Hmm, this sounds the most plausible. I'll bring it to the attention of
the mechanic so he can look further.
Many thanks to the others who responded, too.
Janie
Earle Horton wrote:
> Your vacuum reservoir is collapsed, or there is a vacuum leak.
the mechanic so he can look further.
Many thanks to the others who responded, too.
Janie
Earle Horton wrote:
> Your vacuum reservoir is collapsed, or there is a vacuum leak.
#15
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
Hmm, this sounds the most plausible. I'll bring it to the attention of
the mechanic so he can look further.
Many thanks to the others who responded, too.
Janie
Earle Horton wrote:
> Your vacuum reservoir is collapsed, or there is a vacuum leak.
the mechanic so he can look further.
Many thanks to the others who responded, too.
Janie
Earle Horton wrote:
> Your vacuum reservoir is collapsed, or there is a vacuum leak.
#16
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
Hmm, this sounds the most plausible. I'll bring it to the attention of
the mechanic so he can look further.
Many thanks to the others who responded, too.
Janie
Earle Horton wrote:
> Your vacuum reservoir is collapsed, or there is a vacuum leak.
the mechanic so he can look further.
Many thanks to the others who responded, too.
Janie
Earle Horton wrote:
> Your vacuum reservoir is collapsed, or there is a vacuum leak.
#17
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
Hmm, this sounds the most plausible. I'll bring it to the attention of
the mechanic so he can look further.
Many thanks to the others who responded, too.
Janie
Earle Horton wrote:
> Your vacuum reservoir is collapsed, or there is a vacuum leak.
the mechanic so he can look further.
Many thanks to the others who responded, too.
Janie
Earle Horton wrote:
> Your vacuum reservoir is collapsed, or there is a vacuum leak.
#18
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
The older Jeep Cherokees (88-92) had a vacuum reservoir inside the
right front bumper. Two vacuum lines went from there to the HVAC and
other things like the speed control. The lines went under/behind the
battery. Over time the line wore out (acid ate through) and the Jeep
had both the HVAC and speed control problem. Look at the vacuum lines
then see if there is still a vacuum reservoir.
JB wrote:
> Hmm, this sounds the most plausible. I'll bring it to the attention of
> the mechanic so he can look further.
>
> Many thanks to the others who responded, too.
>
> Janie
>
> Earle Horton wrote:
> > Your vacuum reservoir is collapsed, or there is a vacuum leak.
right front bumper. Two vacuum lines went from there to the HVAC and
other things like the speed control. The lines went under/behind the
battery. Over time the line wore out (acid ate through) and the Jeep
had both the HVAC and speed control problem. Look at the vacuum lines
then see if there is still a vacuum reservoir.
JB wrote:
> Hmm, this sounds the most plausible. I'll bring it to the attention of
> the mechanic so he can look further.
>
> Many thanks to the others who responded, too.
>
> Janie
>
> Earle Horton wrote:
> > Your vacuum reservoir is collapsed, or there is a vacuum leak.
#19
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
The older Jeep Cherokees (88-92) had a vacuum reservoir inside the
right front bumper. Two vacuum lines went from there to the HVAC and
other things like the speed control. The lines went under/behind the
battery. Over time the line wore out (acid ate through) and the Jeep
had both the HVAC and speed control problem. Look at the vacuum lines
then see if there is still a vacuum reservoir.
JB wrote:
> Hmm, this sounds the most plausible. I'll bring it to the attention of
> the mechanic so he can look further.
>
> Many thanks to the others who responded, too.
>
> Janie
>
> Earle Horton wrote:
> > Your vacuum reservoir is collapsed, or there is a vacuum leak.
right front bumper. Two vacuum lines went from there to the HVAC and
other things like the speed control. The lines went under/behind the
battery. Over time the line wore out (acid ate through) and the Jeep
had both the HVAC and speed control problem. Look at the vacuum lines
then see if there is still a vacuum reservoir.
JB wrote:
> Hmm, this sounds the most plausible. I'll bring it to the attention of
> the mechanic so he can look further.
>
> Many thanks to the others who responded, too.
>
> Janie
>
> Earle Horton wrote:
> > Your vacuum reservoir is collapsed, or there is a vacuum leak.
#20
Guest
Posts: n/a
Re: 99 Cherokee HVAC Problem
The older Jeep Cherokees (88-92) had a vacuum reservoir inside the
right front bumper. Two vacuum lines went from there to the HVAC and
other things like the speed control. The lines went under/behind the
battery. Over time the line wore out (acid ate through) and the Jeep
had both the HVAC and speed control problem. Look at the vacuum lines
then see if there is still a vacuum reservoir.
JB wrote:
> Hmm, this sounds the most plausible. I'll bring it to the attention of
> the mechanic so he can look further.
>
> Many thanks to the others who responded, too.
>
> Janie
>
> Earle Horton wrote:
> > Your vacuum reservoir is collapsed, or there is a vacuum leak.
right front bumper. Two vacuum lines went from there to the HVAC and
other things like the speed control. The lines went under/behind the
battery. Over time the line wore out (acid ate through) and the Jeep
had both the HVAC and speed control problem. Look at the vacuum lines
then see if there is still a vacuum reservoir.
JB wrote:
> Hmm, this sounds the most plausible. I'll bring it to the attention of
> the mechanic so he can look further.
>
> Many thanks to the others who responded, too.
>
> Janie
>
> Earle Horton wrote:
> > Your vacuum reservoir is collapsed, or there is a vacuum leak.