Stuck on Defrost

[TurboTJT]

MY Heat/AC system is stuck on defrost with air only going to the windshield.
Moving the HEAT/AC control leaver activates the heater or AC compressor OK but the vents will not switch the air, they are stuck at defrost!
Any easy fixes here without tearing out my dash & duct work ?

 

[jlasinski]

I think I have the same problem. I am only getting air to defrost and to the floor. My controller is the automatic climate control system though. Thanks, John

 

[TurboBuRick]

Under the hood on the passenger side there are 2 hard plastic vacuum lines that run around the heater box and go into the car. One line supplies vacuum to the hvac controls to operate the vents. The other line goes to the heater control valve.

It's common for this plastic line to get brittle and break. Trace it out. If you find one, you can use a small piece of rubber rubber vacuum hose to connect the broken ends.

Ideally a small hand held vacuum pump is the real way to test these circuits.

 

[sshoureas]

did you see this thread a few posts down from yours:

http://www.turbobuick.com/forums/ge...op-defrost-vent-floor-vent-switches-back.html

 

[williambavila]

did you see this thread a few posts down from yours:

http://www.turbobuick.com/forums/ge...op-defrost-vent-floor-vent-switches-back.html

behind your glove box there is a valve you can manualy change where it blows if you cannot figure it out.

 

[CST 03]

I had the same problem a while back and my cruise quit working also. I was able to track the vacuum lines and fix it. Mine was more on the driver side close to the Fire Wall.

 

[696]

Under the hood on the passenger side there are 2 hard plastic vacuum lines that run around the heater box and go into the car. One line supplies vacuum to the hvac controls to operate the vents. The other line goes to the heater control valve.

It's common for this plastic line to get brittle and break. Trace it out. If you find one, you can use a small piece of rubber rubber vacuum hose to connect the broken ends.

Ideally a small hand held vacuum pump is the real way to test these circuits.

Mine was pinched (due to my own doing), after I heated it up and got it back in shape it works like new.