TheGreatGazoo

Does a 89 xj have a HVAC vacuum check valve. I can hear my jeep hvac doors open and close while driving. when I step on the gas I can hear the door by the passenger side kick panel creak open and close. I don't think I have a vacuum leak because when I disconnect the vacuum hose from the intake and hook up my mighty vac and put 20 in hg on the hose and it will hold the 20 inhg vacuum for 30 minutes when I cycle the controls it will only loose about 1-2 in hg. when I bring them back to off its at 15 inhg and it will hold that without dropping at all for 30 minute. so I'm thinking I have a bad check valve some where between the intake connector and the vacuum canister in the front bumper. I traced the hose and there seems not to be one.
anyone have a hvac vacumm diagram?

cruiser54

Yup.

cruiser54

this?

TheGreatGazoo

Hey crusier, do you know if that check valve is an inline check valve or part of the hose barb on the intake manifold. cause I cant find mine anywhere. and since I am the only one that has been working on this xj for the last 8 years I wonder if this was my crappy heat problem the whole time. while driving on the highway warm air but at idle the heat worked great. I remember my dad complaining about it every winter when h owned it.

cruiser54

I don't think they did have it in 88. You could always add one. Sure the vacuum ball is good?

TheGreatGazoo

yea I put 20in hg in the vacuum ball for a half hour and it didn't budge.

cruiser54

Can't beat that!!

Sometimes the HVAC control can leak.