W126 Climate Control
 

83 300SD

I can't get the AC to blow cold air only hot. I've replaced the monovlave and every once in a while everything will work great and the AC works fine. But these occasions are getting further and further apart. I can punch buttons and get it kick on the AC, but after a while its back to hot air. The climate control unit will constantly click, click, click click by itself at about 3 times a second. I recently bought a used climate control unit off of Ebay and took it apart and inspected all of the solder joints (whick looked good) and it does the exact same thing. Did I buy another broken climate control or is there something else causing the thing not to work properly?

Wrong pressure of AC coolant?
 

Hi,
my guess is your coolant pressure is low, did you check?

Yea the coolant is fine. The car will blow cold air sometimes and then switch to hot. Just like your moving the temperature wheel.