I've recently purchased a 1976 Cadillac Coupe Deville. I noticed that the previous owner took the vehicle to a mechanic that really had no idea on what they were doing with this vehicle. I've been able to correct 90% of the issues. My final issue is the A/C. Since no one carries or sells R12 anymore, I've been forced to do the R134 conversion. Everything has been successful for the most part but now the A/C will not blow cold anymore regardless of what setting it is on. The switch tested fine, the pressures are good. I'm leaning more towards a vacuum issue. I did noticed that the heater control valve has no vacuum to it and i'm curious to know if this may be an issue. I did notice as well that this was a "California emissions vehicle." Would anyone know how to get a hold of a vacuum diagram so i may troubleshoot? Thank you!!! Any advice or help is appreciated.

 

The old "Comfortron " automatic temperature control not the best. Do you have FSM? If you remove glove box you will see programmer it is all vacuum control. You can look to see if door will move. and if vacuum is reaching vacuum motor. There is a adjustable potentiometer made to control head. there is also an in car sensor. If airflow is switching through the different modes vacuum is most likely not the cause. Hot water valve only gets vacuum when in full cold max a/c. There is also a temp switch to keep blower off until engine temp reaches 168* except in defrost.