Anyone owns a 2003 SL500 with the working AC and don’t mind to help me verify a few things with the AC compressor clutch functioning and reply to this thread would be appreciated. Thanks, --Hung

1) With the engine off see if you can spin the AC compressor clutch (the middle plate in the middle of the AC compressor pulley) by hand.

2) With the engine running and the auto climate control “AC off” switch is activated (the “AC off “ red lamp is on), verify (watch) if the AC compressor clutch is engaged (spinning with the pulley) or not.

the 2003 sl has a clutchless hub, the compressor spins all of the time and turns on and of internaly by an electrical pressure valve. The hub in the middle of the compressor is only a break away safetly if the compressor seizes.

Thank you very much for the explanation Jayauto. That would explain what I observed.

Would anyone know how can I test the pressure switch for this car and how to bypass the pressure switch. I think this car have a combo pressure switch on top of the receiver/drier with both Hi and Lo?

There are four wires to the connector, I think, they are Brown/Grey, Blue, Yellow and Yellow/Green.

Thanks,