'89 420 SEL - A/C question
 

I have sporadic problems with the A/C compressor not cutting on my 89 420SEL. Usually, when the car is cold, the A/C engages fine. The problem occurs when the car has been driven, turned off, and then restarted when the engine is still warm - many times the A/C will not kick on. When the A/C does engage, it cools down fine. Any suggestions would be appreciated. Many Thanks...

The A/C has a sensor that measures pressure in the system and only then will it tell the clutch to engage and the compressor to activate, it seems that your unit is on the edge of that pressure reading for any number of reasons, sensor going bad, minor leak, when the engine compartment heats up it changed the ambient atmosphere and initiates a pressure changed under the hood, if it was my car I would first locate the sending unt along the A/C system and clean all contacts and run the A/C, if not you have to take it in and have it charged and checked for leaks, unless you have experience and the equipment in A/C do not tackle this job yourself, let us know what the outcome is.

Jerry,

Thanks for your quick response. I'll try cleaning the contacts on the sending unit and will let you know how that works. Appreciate you taking the time to get me pointed in the right direction. Have a great day!
John