Hi:
I have a 1990 wagon. The A/C is not leaking. The compressor clutch was replaced about 4 years ago. I'm having trouble again with the clutch. It tries to come on and power is going to it. It works intermittantly, and at times just clicks in and out doing, partial rotations. If the engine is just at idling speed, it may stall when the clutch tries to engage. What I am wondering is, if the problem could be caused by excessive drag from inside the compressor, or if it is simply an electrical problem in the clutch itself. I wouldn't want to replace the clutch and then also have to replace the compressor later on.
Thanks for your advice!

I would try direct jumping the the low pressure switch and see if the compressors runs. If it does, you either have a bad low pressure switch or are low on freon. One other way you can test is to direct wire the compressor to the battery and see if the compressor runs. Both are just tests so don't continue to run the car and A/C with either the lower pressure switch jumped or the compressor direct wired to the battery.

Let us know what you find.

Here's a possible test:

The idea is to get things so that you can turn the pulley by hand, with clutch engaged, in order to detect if the compressor internals are dragging or attempting to lock up.

To do this you would have to remove or severely loosen the a/c drive belt, and jump the low-pressure cut off switch. Then with the key in "Run" and the a/c on, the compressor should engage if (1) the time delay has elapsed, and (2) you jump the low pressure switch.

See how easily the compressor turns. You can tell if the pulley/clutch are engaged. If the clutch is not engaged, the test is meaningless.

Good Luck,

Bob

:>)