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Only defrost setting works on hvac controls?

Raymont

NAXJA Forum User
Location
La Crosse WI
1997 jeep cherokee 4.0l.......

Like the title says, only defrost works. My guess is that its a vacuum leak some where, is this a common thing on xj's? Just got it and im new to the xj world.
 
You got it, vacuum leak. Default position is defrost. Fairly common, just have to track it down.
 
first 2 places to check....... vacuum canister mounted to pass side of front bumper. make sure it hasnt come undone.
2nd place is where the hard vacuum line runs behind the battery going to the canister. Bad about getting holes rubbed in them there.
 
Vacuum @ canister, canister is leak free.

Vacuum all the way to the switch in dash. I can hear the door in the hvac system move when I switch it to pannel. Here's what it does.


Move selector switch to Pannel. 80% of air comes out of defrost, 20% out of pannel

Move selector to floor. 99% air out of defrost, 1% air to floor on passenger side.

Anyone ever had a selector switch fail?
 
Vacuum leak. Check the entire line, especially near the battery - the acid tends to corrode the line and cause leaks.
 
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