Sanden AC Compressor Clutch Operation

[Sunroof]

Probably a ridiculous question, but do the Sanden AC compressors have a built in high pressure or temperature turn off switch, or is my AC compressor clutch going?

I was charging my system last night, which only took 30 ounces of R134 and I noticed that the clutch on the compressor would stop on occasion. I had to turn off the switch to reactrivate! One time I thought I saw some smoke from the clutch area, but it could have also been some smoke from lubrication that dripped and was heated up on the block.

Just how do the Sanden Compressors operate or am I in trouble with a bad clutch here! If it is a sign that the clutch is going, it is worth replacing the clutch or just cheaper to buy a rebuilt unit?

Thanks
Bob

[cmonref]

Was the temperature set on a temperature higher than the minimum? If so, the thermostat may have been cutting the compressor out. Check for a voltage at the clutch wire -- 12v engages the clutch, 0v disengages it.

What were the low and high pressures on your guages when the clutch cut out? A 134 system should have a low-pressure cutout switch that disengages the clutch when low pressure is sensed -- as a protection for the compressor to keep it from running without refrigerant. The low-pressure switch may be external or internal to the compressor.