Hi. I posted this question on the vintage board yesterday. Thought I'd try here. I have a 79 280CE purchased with the AC already converted to 134. Last Summer, a home recharge and it worked fine for several months, needing a top off of 134 again in Sept. I didn't need AC until yesterday, and a recharge attempt failed as the compressor/clutch wouldn't kick in in order to suck the freon in. Tha advice I got was to bridge the connection on top of the dryer which would bypass the compressor shut off. Ok, tried that and also tried bridging the two wires to the dryer by pushing a piece of speaker wire into the female spade connections didn't cause the compressor to kick in either. What am I doing wrong? Help?

I expect that this car still has an old York style 2 cyl. compressor. These critters just won't hold up to the additional pressure of 134. Been there, done that. I have reverse converted one and replaced the compressor after totally and thoroughly flushed the system, changed r/d, added mineral oil, evacuated and charged.

The good news here is that these compressors are cheap.

Without the engine running, start by jumping 12 volts directly to the clutch and see if it clicks. Without voltage applied turn the compressor by hand and see if it is free. If you are successful with both of these, start tracing the clutch circuit and don't overlook checking the fuse.

Good luck,