A/C Compressor Clutch

So I bought this Golf without the AC working. Refrigerant is charged. Found AC compressor clutch won't engage. Had no power going into clutch. All fuses were good. Read that the FCM is a common failure, so I replaced that. Now I have 12+ volts and good ground going to clutch. Tested AC again but still doesn't engage clutch. Checked resistance to coil and it had 4ohms which seems to be the spec according to other threads. Seems like maybe a bad clutch?

Looking for some insight on the repair, and possibly recommendations on a decent clutch or compressor kit for sale out there.

Thanks!

If the coil has ~4 ohms of resistance then the odds are it's good. You can QUICKLY jump it to +12v with the connector unplugged (don't leave it engaged for a long time this way) and see if it clicks in.

I suspect a wiring problem if the clutch shows proper ohms -- where did you check for voltage? The running voltage out of the FCM for the clutch, into a working (not open) coil is closer to 9v than 12.

When I checked voltage I was checking at the 2 wire connector closest to the AC compressor. Load tested wires. No voltage drop from power lead or ground. I've owned this car for a year without AC and idk how long the previous owner didn't have AC. Maybe the clutch itself is seized?

Thought about giving it some love taps with a hammer to see if maybe it could be that simple.

The only thing the previous owner said about the AC was that it made a noise before it quit working.

I assume you've tried turning the center section by hand and it rotates?

It's POSSIBLE the coil has 4 ohms but isn't pulling in the clutch, but not very likely. It's also possible the clutch is toast, the compressor is locked up and the "noise" was it destroying itself when attempting to engage with a locked compressor

Yes I could spin the center of the compressor easily when I was doing my testing. Hoping I can get some more time to check this out today.

Well I haven't really driven the golf since I changed the FCM. Went to move it yesterday and the battery was stone cold dead. Charged it, moved the car, and parked it again. Went to start it today and it was dead again! So I get it started and drive to my local auto parts store to have them test the battery, and the battery tested fine.

So I figured this had to be a parasitic draw. Used my amp clamp and found 3 amps with key off from the cable that feeds the fuse box on top of the battery. Started removing fuses above battery one by one and found the fuse second from the left was the circuit causing the draw. I read this feeds the relays. Start pulling interior fuses one by one and found fuse #16 for the AC clutch was the culprit. Reinstalled the fuse and unplugged the AC clutch, and draw goes away.

Does it make sense that the AC clutch can draw with the key off? Wouldn't it need voltage from the FCM for the clutch to pull the amps?

It was late and I didn't want to get the car in the air to see if the FCM is supplying the clutch coil with power constantly, but I imagine that should be my next course of action.

Not sure if it's the switch inside stuck in the closed position.
I say that the clutch is fried like the solenoid sticking in the crank position on a starter.

I would expect to be a pump too.
Take it to the local AC shop and have them test the pump maybe

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When I was looking into buying a FCM, I founds lots of complaints from people who bought them on flea-bay that the cheap FCM switch internals kepts the clutch engaged, thus draining out the battery. If your car is off and it's draining electricity, unplug the FCM and see if it still does that. Could be a bad FCM.

alex_tdi said:

When I was looking into buying a FCM, I founds lots of complaints from people who bought them on flea-bay that the cheap FCM switch internals kepts the clutch engaged, thus draining out the battery. If your car is off and it's draining electricity, unplug the FCM and see if it still does that. Could be a bad FCM.

Click to expand...

I normally never buy the cheap eBay electronics but I bought a window switch panel a while back and had good luck so I tried to get this FCM from eBay too. I'm guessing it's just the case of buying a low quality FCM.

Anyone know where to source a decent quality one? I can't imagine the auto part stores having anything much better.

TdiRabbi said:

Anyone know where to source a decent quality one? I can't imagine the auto part stores having anything much better.

Click to expand...

www.idparts.com

Fuse 16 does feed the fan control module and the FCM does feed the clutch.