A/C and heat only comming out of defroster vents

Anyone know why all air will only come out of the window defroster vents and not the dash mounted vents in all positions? Thanks!

i cant answer that exactly, but when i got my xj, when i switched to the vents sometimes the lil flapper under the glove box failed to close all the way. i had to replace the bolt into the seat or soemthing, i forgot im sorry. check under the dash for stuck flaps i guess.

Heater controls are vacuum operated. The default if vacuum fails is the defrost outlets.

You have a vacuum leak. Check all vacuum lines, and the vacuum reserve "blimp" located behind the front bumper on the passenger side. First lines to check are the ones to the blimp where they run under the battery tray.

dandecicco said:

Anyone know why all air will only come out of the window defroster vents and not the dash mounted vents in all positions? Thanks!

Click to expand...

you ever fix this cause I am having the exact same problem

The vaccuum line on the intake manifold came off. I fixed two of these this weekend. It is on the left side of the intake, look for a dangling line, use a zip tie to secure it. I bett your cruise doesn't work either. They are all connected to the same problem

I had the same problem and got it fixed once while under warranty. They had to replace the blend air door mechanism. It has happened again but not under warrenty and I haven't fixed it yet. Mine will randomly go to defrost and then eventually come back to the AC vents. It really sucked in Phoenix, but I got it fixed there under warranty. Now I'm just dealling with it. I plan to try and fix it eventually but it requires removal of most of the dash and trim to get up in there.

Jim

I second the vacuum leak. Check the hard line that runs under the battery tray real close. That's where mine cracked. Real common. Also check all the connections on top of the engine as mentioned.