190 e 1993 mercedes 2.3

Jeff, I hate to be the one to break the news to you. AC compressor is bad. The compressor has a speed sensor on it's rear, it reads the speed and sends a signal to the climate control relay, there the speed is being compared to that of the crakshaft. What's the relay reads that the RPM of the compressor is different and thereby the relay cuts the compressor off. This is a safty set up so that if your compressor locks up you don't burn up the belt then lose alternator and waterpump. All cars that have that one accessory belt set up have a speed sensor in the compressor. Let the engine warm up, shut off the car, re-start the car and have the hood open, you will notice that the compressor kicks in for 2 to 3 seconds and then cuts off and won't come back on again until you repeat the process. Don't bother replacing the speed sensor, it will NOT fix the problem. Martin Autobahn Auto

Just figured out that it's not when it's not when the car runs hot but when the belt slows it cuts off.Could it be a lose belt?

Jeff

Yeah that seems possible...

Also could be the serpentine belt tensioners is spun. The tensioner relies on a rubber elastomer insert to tension the s-belt. If this rubber piece breaks down then the tensioner no longer applies enough force.

Hope this helps. Marty