I bought a 1987 260E yesterday and the A/C is not working. The electrical connector to the compressor was disconnected so I connected it, but still no dice.

The system was converted to R134a several years back, so I thought maybe a recharge was needed. I connected my gauge and it was low. As I began to add R134a refrigerant the A/C began to turn on but it was squealing terribly. The air coming out the vents is hot so it is obviously not working.

How can I determine if I need to replace the compressor? I am thinking of replacing the compressor with an R134a Denso unit.

Thanks, Bob

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1987 Mercedes 260E (W124) 213,000 miles
1971 MB 220 w/ 4 spd manual (W115) "Suzy" (sold)