Lotsa vacuum!! - AUSJEEPOFFROAD.COM Jeep News Australia and New Zealand

brizXJ · #1 15-04-2007

I have noticed that the vacuum to the heater switch on my '96 Cherokee 4L seems to be present even 12 hours after switching off...I have never noticed this before and I was surprised to find that if I pull the line off the rear of the actuator the system contains quite a lot of suck....I would think that with the heater not being used the actuator would be normally closed, not open....can anyone look to see if theirs is open or closed when the engine is shut down please?
Thanks.

hillsjeep · #2 15-04-2007

Mine's in the same position as your's.

brizXJ · #3 15-04-2007

Thanks Hillsjeep....maybe its normal, everything seems to be working ok (air-con and heater). I guess it does suggest that my vacuum system is 'airtight' anyway.

AussieRCBasher · #4 15-04-2007

The vacuum line on the intake cracks and pops off, make sure this hasnt happened to you as mine always came off. Also if you heater switch diess get one off a commodore as its the same, dont go to jeep and be fooled into 150 for a new one.

Mine changes as its onto the LPG so it converts the water for the LPG converter.

#5 15-04-2007

Mine must be in the dash somewhere, I don't have a tap like that in the engine bay. Must get in and find it one day though cause I reckon the left centre air vent is getting a little heat. It definitely feels hotter than the right. Weird.

brizXJ · #6 16-04-2007

Aussie you may not have read my posting correctly...I dont have a problem with a lack of vacuum, my query concerns the fact that vacuum seems to be at the heater switch all the time, even after the engine is shut down...the switch is held against the spring, if I pull the hose off the switch returns to home position....and yes, I too, brought the Commodore one, it comes from the same factory.

Gojeep · #7 16-04-2007

There should still be vacuum after weeks. Mine does so long as the brake pedal is not depressed. There is a vacuum tank behind the bumper to give brake pedal boost during starting in case you have a manual and are not using the handbrake. Everything also like the heater control also benefit from this but it not the reason for the tank.