HVAC controls bleeding down?
Thread Starter
CF Veteran
Joined: Apr 2016
Posts: 1,820
Likes: 60
From: Pasquotank, NC
Year: 1990
Model: Cherokee
Engine: 4.0
HVAC controls bleeding down?
1990 4.0l
When I shut the Jeep off with the heat running on floor (verified it is blowing on floor) it sounds like a hissing sound from the passenger foot well like a blow off valve. Not loud, just the diminishing air escaping sound. Clear as mud? Is this normal or should I look for a leaking vacuum component?
With the engine off I have pulled a vacuum on the line going into the vacuum ball and it held, no leaks.
When I shut the Jeep off with the heat running on floor (verified it is blowing on floor) it sounds like a hissing sound from the passenger foot well like a blow off valve. Not loud, just the diminishing air escaping sound. Clear as mud? Is this normal or should I look for a leaking vacuum component?
With the engine off I have pulled a vacuum on the line going into the vacuum ball and it held, no leaks.
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 101
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
1990 4.0l
When I shut the Jeep off with the heat running on floor (verified it is blowing on floor) it sounds like a hissing sound from the passenger foot well like a blow off valve. Not loud, just the diminishing air escaping sound. Clear as mud? Is this normal or should I look for a leaking vacuum component?
With the engine off I have pulled a vacuum on the line going into the vacuum ball and it held, no leaks.
When I shut the Jeep off with the heat running on floor (verified it is blowing on floor) it sounds like a hissing sound from the passenger foot well like a blow off valve. Not loud, just the diminishing air escaping sound. Clear as mud? Is this normal or should I look for a leaking vacuum component?
With the engine off I have pulled a vacuum on the line going into the vacuum ball and it held, no leaks.
Have you tried it with the HVAC controls off before hutting down?
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 101
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Turn the controls OFF before shut down as a regular operation.
Remove the cover off the blower resistor (see pic) so you can see the recirc air door actuator. See post #2.
With the engine running and the controls to heat, shut down the engine and see/hear if the recirc air door actuator is your problem.
Do the same with the controls OFF.
.
Remove the cover off the blower resistor (see pic) so you can see the recirc air door actuator. See post #2.
With the engine running and the controls to heat, shut down the engine and see/hear if the recirc air door actuator is your problem.
Do the same with the controls OFF.
.
Last edited by CCKen; Dec 3, 2016 at 09:09 AM.