I am new to the forum, thanks for your help. I had some salt water spray onto my dash (I've since rinsed it good) and now my a/c is acting up. My van has a rear unit which still blows cold, no problem. The front unit blows hot air all the time now. I pulled the dash and pulled the temp control switch but really don't know how to go about testing it. The fan speed switch works fine and the switch to turn the a/c to floor, defrost, etc. also works fine.


Because the rear a/c is blowing cold, I assume it's not the compressor. Your thoughts are appreciated.

 

if the blend doors are vacuum controlled; apply vacuum to the vacuum dashpot for the blend door and see if it moves the door.
start the vehicle and make sure the vacuum supply line to the dashpot is getting vacuum.

 

I replaced the temp control switch and it works now. Thank you.