Were your readings in AC voltage? I would not critique the speed sensor with voltage alone. It should be a sine wave with .3v peak to peak. A scope is a much better tool. The system does need to be discharged and most speed sensor problems are from rebuilt compressors that have the distance from the sensor to shaft defective. Speed sensor problems are common but they are almost never the sensor itself. It is more likely a belt or slipping clutch problem
The symptoms you describe characterize a loose or worn belt. Any belt flop will set off the speed sensor trigger.
It is the diesels that have the power switched Klimas, but I don't think yours is one of them. The problem is simple though since yyou do have moments of compressor action. During a moment of proper funtion look at the signalpassing through the low pressure switch. It will either be a 12v signal from the Klima that is taken to .15-.2v by the pushbutton controller. Or it will be a 12v signal that originates at the pushbutton controller. View the voltage at the switch in both off and on (working properly) condition and you will see which system you have.
Bosch Master, ASE Master, L1
33 years MB technician
Last edited by stevebfl; 07-06-2003 at 12:33 PM.