I have read a lot of posts about Blend Door Actuators and vacuum line contamination, but I do not recall ever hearing anyone with this particular problem...with the selector set to MAX A/C the cold air comes from the dash vents and the defroster somewhat. As RPM increase (and vacuum decreases) the dash vents cease to flow any air and the defroster gets it all. Return to idle, or just coast at speed with no throttle, and the air flow returns to the dash vents.

Has anybody else ever dealt with this? Any suggestions as to cause or cure?

Thanks Much!

 

Sounds like a vacuum leak somewhere. the default when all vacuum is removed is Defrost.


So it sound like at idle it is working partially but when the vacuum decreases it cannot keep up and defaults to defrost setting.


Check next to your ABS module on the left fender. There is a vacuum hose that is supposed to plug into a vacuum reservoir located behind the ABS module within the fender that often comes unplugged.

 

Thanks for the reply. I agree, it is a vacuum leak somewhere, I was just hoping someone might have had a similar problem and could say, "It's the Gafrabus"...or "its the Gazinta !"

I've checked all the easy to access under hood hoses and the ball tank...no luck. Guess it's time to tear the dash apart.