Cadillac Repair: 1991 Cdilac Deville-Air Conditioning, 134a freon, r 12 freon

Question
I had a repair shop change my sys. from R-12 to R-134. They changed the quick connects and supposedly put a vacuum on it. Also changed the clutch assembly. I went on vacation. It ran for 2-days and the compressor LOCKED up.Was I wrong to change to R-134 and I'm going to change out the compressor to a new one. Do I need to change the Dryer/Accumulator out too?

Answer
Re move the compressor, orfice tube, Receiver/Dryer (accumulator)and FLUSH out all the lines with an A/C flushing agent which you can purchase at any auto parts store.


You also need to change out the:

Compressor.
Receiver/Dryer (accumulator)
orfice tube.


NOTE: You CANNOT convert this year and model vehicle from R-12 to R-134a because the LOW PRESSURE SENSOR is NOT calibrated to interpret the molecular difference that is in R-134a freon. You WILL have problems with the A/C system and will constantly get a CHECK ENGINE ligh illumination on the dash.

There is NO new sensor available to replace the original. You are STUCK to use ONLY R-12 freon in this system.