AC and heat only blow out the defroster

This happened before but eventually it went back to normal and the controls worked fine.

Why is this?


I have two Jeeps, neither one have properly functioning AC and it's August, good thing it's only 60º in Chicago, today.

Mine did the exact same thing... That blimp thingy behind the bumper on the passenger side, has a ton of vaccum lines running to and from it. check all of those lines. Mine had one broke and I fixed it and now it works perfectly. It is supposed to act as a capacitor type deal and store "energy" and hold to duct thingys open that control where the moving air goes, through the front vents or the defroster vents...

Tom

Will do that, thanks!

Listen under the hood woith the engine running for a whistle, I would check the vacuum lines where they run along the passenger side of the engine area for melted of worn through tubing.

BTW...Notice i did not make a crack about the whistling coming from between your ears?? See I can be good.
:doh:

Rev

You did not state exactly when this happens..... If this happens when you are driving with the engine under load.... then another possibility could be that YES you have a vacuum leak, but there should be a check valve in the vacuum line supplying the climate controls. The check valve is either not working properly or is not there. The check valve should maintain vacuum on the downstream side of the system to keep the system dampers in the selected position until vacuum is restored (assuming you dont select a new position).
The most common places to check for vacuum leaks are under battery tray and vacuum storage canister behind the front bumper on the passengers side.

Hope this helps......