A/C randomly blowing through Defroster or Floor

long_tall_texan · **Posted:** Sun Apr 01, 2012 8:53 pm

Took a road trip in my KJ yesterday. Had the Air Conditioner on recirculate. all of the sudden, it switches to blowing through the floor instead of the dash vents. Then it switches to the defroster vents instead of the selected dash vents. I change the selector knob a few times, no change in where the air blows out. As I come into the next town, and slow down, it switches back to the dash vents. I get back up to speed above 65 MPH, and it swaps to defrost again. Every time I slow down, it operates correctly. Every time I get up to highway speed, it gets a mind of its own, and swaps randomly between dash, defrost, and floor. Mostly staying on defrost, but just randomly changing as I drive. I assume this is some sort of a vacuum leak. Any ideas as to where to start?

lfhoward · **Posted:** Sun Apr 01, 2012 10:06 pm

That sounds like a vacuum leak to me too. I had this problem on my old XJ and it was the vacuum hose that connected to the vacuum ball behind the front bumper. I have no idea if there is a similar part on our Jeeps, but it might be worth a look. Once the hose was replaced, the vents worked normally.

Billwill · **Posted:** Mon Apr 02, 2012 3:18 am

lfhoward wrote:

That sounds like a vacuum leak to me too. I had this problem on my old XJ and it was the vacuum hose that connected to the vacuum ball behind the front bumper. I have no idea if there is a similar part on our Jeeps, but it might be worth a look. Once the hose was replaced, the vents worked normally.

Yes there are vacuum pipes leading into the cab for the vent controls.
The OP needs to trace the pipes and look for leaks somewhere.

long_tall_texan · **Posted:** Mon Apr 02, 2012 11:54 am

Sounds like a perfect opportunity to take advantage of that bumper to bumper $50 deductible warranty that the dealer through in to sweeten the deal back when I bought it new. Much easier to do that than me trying to track down which hose has a leak.

A/C randomly blowing through Defroster or Floor

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