A/C Stuck on Defrost Vents

[89 Manche]

I hate to keep asking everyone questions, but I'm going to nonetheless, so please bear with me. :popcorn:

 

The Comanche I'm looking at has developed a problem with the A/C. It used to work just fine, but the last time I test drove it I was cycling through the heat & A/C controls th A/C got stuck on defrost. It seemed to still be blowing cold air, but no matter where I set the discharge, it would just blow throught the defrost vents at the windshield.

 

What might this problem be and does anyone know about what I would cost to fix?

 

Here in Texas, I need A/C 10 months out of the year.

 

Thanks for your help. ---------> This board is GREAT, by the way!

[HOrnbrod]

Right front side, check the plastic vacuum line where it passes through the radiator cowl and goes to the vacuum cannister behind the bumper. The vacuum line breaks there because of friction - common problem.

[Pete M]

I hate to keep asking everyone questions, but I'm going to nonetheless, so please bear with me. :popcorn:

 

Please refer to Rule #2. :cheers:

 

http://comancheclub.com/forums/viewtopic.php?t=1239

[Eagle]

Almost certainly a vacuum leak -- the flappers are vacuum operated. The line to/from the vacuum reservoir is a prime suspect, especially right near the battery, but if you don't find the leak there check the reservoir itself (might be a round ball about the size of a softball, or might be a sausage-shaped thingie that's like the softball extruded lengthwise -- also referred to affectionately as "the blimp"), and then the rest of the vacuum lines between the reservoir and the flappers.