Heat only blows from the defroster? Can't switch to vent or floor??

Hello all. I have a 1990 Jeep Cherokee XJ Pioneer, IL6, 5 Spd. The other day I noticed that when I turn on the heat it only blows on the windshield for defrost no matter what position the selector is in. It just happened. Not sure why. When I move the selector to vent or floor, what controls how the air is diverted? Any help appreciated! Thanks as always.

I have a similar issue, i understand its related to a vacuum leak. The diverter is controlled via vacuum. The defroster is the default position for air, so the fact that its going only there could indicate there isnt enough vacuum to otherwise control it.

Or the simpler answer might just be that your lever is broke off inside or something like that.

Thanks sporkton! I was planning on pulling out the panel this morning.

1990Pioneer said:

Thanks sporkton! I was planning on pulling out the panel this morning.

Click to expand...

Don't do that just yet. There's a vacuum reservoir behind the passenger side front bumper with lines running to the firewall. They crack and break. Start there.

Hi there,
Let me know what you find, my 89 is doing the same thing...(new to me, so no history from the PO)

Warm head, cold feet in NNJ


Mark

SUCCESS! Alright my friends, here's what i did. I checked the reservoir behind the front bumper,checked all of the vaccuum tubing, took the control out of the dash for safe measure. Then it hit me!, I realized that the main vaccuum line coming off of the manifold runs behind the valve cover and the fire wall in an awkward way. I had a new clutch installed about two weeks ago right around the time that my heater started acting up. When I had the control out of the dash I found that there was NO vacuum at all to the control. I found that main line behind the valve cover was PINCHED between the GOD D@#$ tranny and engine!! Obviously happened when they put the tranny back in. I cut out the tubing, spliced it back together and walla!

troutski said:

Hi there,
Let me know what you find, my 89 is doing the same thing...(new to me, so no history from the PO)

Warm head, cold feet in NNJ


Mark

Click to expand...

Use post #4 like the OP did and you'll find the problem.