The A/C is dead, and it looks like the compressor, but I would like some feedback from the a/c gurus. My low side was at about 30psi at 95° outside. The high side was at about 30psi as well. I added some r134. Low side psi went up to over 100psi, and the high side was about the same. It looks to me that the compressor is toast. (it does engage). Other options? If it is gone, I will retrofit to r12. Has anyone done that? It sounds like its change out drier, expansion valve, and compressor in this case, and flush. Orings too. What else?

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1986 300sdl
1984 300sd
1988 300se
1973 vw thing

When the compressor engages you have 100psi on the low and 30 on the high? There is no way your system has enough freon for 1 and if the compressor is engaging its not doing it long enough to create pressure. When it engages it should engage and low side should drop low and high side be about 3 times that. You sound about 3 cans low, freon in a system that hasnt been used in a while will just leak out of weak seals on the compressor front usually as no oil is lubricating it. Also you can not properly fill the system with out the sytem on full high cool and compressor fully engaging as you putting in freon. One done at idle you must have someone slowly hit the accelerator to 2k rpms while adding freon to get 35 low side about at 2k rpms. When you shut the car off at your ambient temp the low side should be pegged on your gage.

I hope this helps.