I checked the inputs at the klima, the compressor speed sensor input is between 0-0.1 v (AC) at idle, it increases to 0.4 or 0.5 at 2000 rpm...the CD says it must be at least 0.3 v at idle (750 rpm)...at rare times the compressor stays on at idle but cuts again if the car driven...
I am not sure if the previous owner had the compressor rebuilt, this is a possibility since the system was converted to r134 professionally (there is a tag and a leak detection process etc..). They might have rebuilt the compressor...
Now, should I "vent" the AC and take off the sensor, what signs of failed sensor should I look for, should I just clean it and change the o ring and reinstall for a test, or the magnetic inside the sensor is old and weak therefor I should install a new one (~ $85)...can I do that while the compressor in the car, it is tight space but I think it is doable??
After that, should I vacuum the system, if it is fixed with the sensor replacement, before charging, or this is process preserve the system cleanliness and no need for vacuum...
Lastly, how about the oil, does vacuum take off oil..
I really appreciate your advice,