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I think the AC compressor clutch on my car might have failed, but wanted to run it by the knowledgeable people on this board to confirm my thoughts/testing process.
MANA AC system on my '93 was converted over to 134a a couple years back and running fine. Just recently, it stopped blowing cold and I noticed the AC led in the cabin was flickering when the button was set to the enabled state. The flickering went away subsequently, but now, even though the led glows orange normally, the AC doesn't blow cold. I visually confirmed that the AC clutch isn't enabling; you can see the center isn't rotating. As a test, I unplugged the high/low pressure switch and shorted the connector by running a wire between the 2 pins. Compressor clutch still doesn't enable. I then unplugged the single wire connector going to the AC compressor and ran battery 12v directly to the compressor input. I believe this is the right way to brute force trigger the clutch? The clutch still didn't enable, but I did notice that when I remove the wire from the positive battery post there's a quick spark. Not sure what too make of that, but doesn't seem right. Does the engine need to be running while testing this? I tested it with the car off, but I figured I'd hear some sort of click from the clutch when applying power to the lead. So has my compressor clutch given it its all and moved on to where ever ac clutches go to in the sky?
I should also note that I checked the AC and cigar fuses and they're both good. So nothing was tripped.
Anyone know what the blue connector goes to that the compressor input leads into? The 2nd wire going into the connector just goes to the clutch. It looks like the blue connector is attached to something, but no idea what it is. Maybe that's the issue rather than the clutch itself?
My not compressor, but show the blue connector and the thing it connects to
I think the AC compressor clutch on my car might have failed, but wanted to run it by the knowledgeable people on this board to confirm my thoughts/testing process.
MANA AC system on my '93 was converted over to 134a a couple years back and running fine. Just recently, it stopped blowing cold and I noticed the AC led in the cabin was flickering when the button was set to the enabled state. The flickering went away subsequently, but now, even though the led glows orange normally, the AC doesn't blow cold. I visually confirmed that the AC clutch isn't enabling; you can see the center isn't rotating. As a test, I unplugged the high/low pressure switch and shorted the connector by running a wire between the 2 pins. Compressor clutch still doesn't enable. I then unplugged the single wire connector going to the AC compressor and ran battery 12v directly to the compressor input. I believe this is the right way to brute force trigger the clutch? The clutch still didn't enable, but I did notice that when I remove the wire from the positive battery post there's a quick spark. Not sure what too make of that, but doesn't seem right. Does the engine need to be running while testing this? I tested it with the car off, but I figured I'd hear some sort of click from the clutch when applying power to the lead. So has my compressor clutch given it its all and moved on to where ever ac clutches go to in the sky?
I should also note that I checked the AC and cigar fuses and they're both good. So nothing was tripped. Anyone know what the blue connector goes to that the compressor input leads into? The 2nd wire going into the connector just goes to the clutch. It looks like the blue connector is attached to something, but no idea what it is. Maybe that's the issue rather than the clutch itself?
My not compressor, but show the blue connector and the thing it connects to
^That connector would be for a pressure switch. It's a normally closed switch that opens when the pressure drops below its set threshold; purpose is to protect the compressor from failure in the event the system loses too much refrigerant (and lube with it). Now if you lost enough refrigerant to trip that switch, it's doing it's job.
To test, you can disconnect the blue connector, and use a jumper wire to connect it's two terminals together. Then try turning on the AC again just to see if the compressor engages, but don't let it run for long . At this point, you still don't know if it's a defective switch or if you're low on refrigerant, so the next step is to hook up a set of AC gauges to confirm. If you've got correct pressures in the system, then that switch has failed. If not, you have a leak somewhere in the system that you need to find/fix and then evacuate/recharge the system
08-01-20, 11:51 PM
