I have a 1994 940 sedan, non-turbo. The a/c compressor clutch stopped functioning one day and has been working intermittently, apparently whenever it feels like it, ever since.

I have found the following tips on brickboard.com and have tested them, still the problem persists:

1. took the clutch off the compressor; everything looked fine
2. apply 12 volts directly to the clutch when it was off the compressor and it worked fine
3. apply 12 volts directly to clutch after the clutch was back on the compressor and it works fine, compressor functions normally, and the air blows cold in the cabin (40-45 deg. F)
4. a/c switch (not blower motor speed selector) in cabin clicks every time it is turned on as if it is activing the a/c system
5. when compressor is running, low side pressure is approx. 25-27, perhaps a little low but now too low/too high to cause either pressure switch to shut down operation
6. bypassed thermal switch at compressor by splicing wire in between thermal switch and clutch and routing it back to the connection in the area under the intake manifold, still no change (intermittent opertion). I saw this as a problem in high temperature geographic locations, such as Florida where the car is driven now, however, we don't have extreme heat this time of year.

Here's the puzzle. When the clutch is disconnected entirely and I turn the a/c on inside the cabin using the button (not blower motor dial), the computer causes the engine and everything else to function as if the clutch was actively engaging the compressor. This includes operating the cooling fan and reving the engine slightly at the intervals when the clutch would normally engage.

Therefore, I believe I can rule out the hi/lo pressure switches, the clutch, all of the wiring, the computer, switches inside the cabin, compressor, etc.

A couple years ago, I also replaced the series resistor under the glove box, and because the malfunction is nothing like when the resistor went bad, I know this is not the problem either.

What am I missing? Can anyone shed light on this problem? I seriously doubt the dealer will have a clue if I take it in for service. Sell it? That's probably next if I can get it fixed first.


1994 940 turbo sedan
1988 760 turbo sedan (for fun)
1996 Jeep Cherokee
2 kids