AC Compressor Clutch Not Engaging

[hoeser]

Had the car about a year with working AC, blew nice and cold, nothing out of the ordinary. Today it suddenly stopped working - compressor clutch will not engage, the compressor shaft feels normal and spins freely. No VCDS codes at all, compressor clutch voltage in VCDS reports +13 and compressor "on" is 1.0 when I have ECON off. I figure if it was a pressure problem VCDS would report something. I've never had any leaks in the system and I use AC all the time and have seen no deteriorating performance.

I strongly suspect I've done something, as I was working in that area with the auxiliary fan controller, I pulled it off the mount and inspected it, and remounted it afterwards. My secondary fan has not worked since I got the car, it doesn't appear to be a problem with the controller as it does output +13V to the fan, and when I tested the terminals on the fan I get an open loop so I figure the fan is shot. The only time it impacts AC performance is sitting in traffic, as I would expect. I haven't pulled the front clip off the car to work on the fan yet.

The AC did work after I reinstalled the fan controller, for about 45 minutes - so it may be a massive coincidence... but I find that hard to believe since I was messing around in there - but as I understand it this does not effect compressor start/stop? Any help sure is appreciated. Could i have bumped or damaged a critical connector for the AC compressor in that area?

[hoeser]

Found the green 1 wire A/C clutch field wire next to the power steering reservoir, looks like the +12 is getting there also. tried manually just jumping directly to the battery but the clutch still wont engage. Damn. I don't think I could have damaged the wire, so it looks like my a/c clutch is probably shot.

[Mille Bornes]

Sounds like you have it figured out

The only other thing you could do is try to check the clutch wire closer to the compressor but I can't picture how accessible that is from underneath

[christianb5s4]

I had a dead auxiliary fan when I first bought the car so I recommend replacing that otherwise your car will start to overheat with AC on in traffic, you do not have to pull the radiator clip out to access it. There's one phillips head screw and you twist it counter clockwise and it'll pop right out.

As for the compressor not engaging, you could also have a bad G89 temp sensor. It's the temperature sensor under the cabin air filter and when it goes bad, it reads erroneously and is a known problem on these cars and causes intermittent or completely non-functional AC.

[hoeser]

I had a dead auxiliary fan when I first bought the car so I recommend replacing that otherwise your car will start to overheat with AC on in traffic, you do not have to pull the radiator clip out to access it. There's one phillips head screw and you twist it counter clockwise and it'll pop right out.

As for the compressor not engaging, you could also have a bad G89 temp sensor. It's the temperature sensor under the cabin air filter and when it goes bad, it reads erroneously and is a known problem on these cars and causes intermittent or completely non-functional AC.

I never thought of trying to pull the auxiliary fan without pulling the front of the car off, it seems crazy tight in there. I will take another look at that, thanks.

As for the temp sensor, I don't think its bad - I literally tried jumping the compressor directly and the clutch did not engage.

- - - Updated - - -

Sounds like you have it figured out

The only other thing you could do is try to check the clutch wire closer to the compressor but I can't picture how accessible that is from underneath

I thought about trying this, it's insanely tight in there though. I fail to see how I could have severed or damaged the wire down load, but you never know.

[DieselElectric]

If you have 12v going to the clutch, but it's not engagine, then you are looking at a failed clutch.

Question is though, did the clutch fail or did the compressor seize?

See if you can turn the compressor by hand. If so, and you are handy, you should be able to get the clutch only from the dealership. Put it into service position, swap, back together without ever draining your refrigerant.

[hoeser]

If you have 12v going to the clutch, but it's not engagine, then you are looking at a failed clutch.

Question is though, did the clutch fail or did the compressor seize?

See if you can turn the compressor by hand. If so, and you are handy, you should be able to get the clutch only from the dealership. Put it into service position, swap, back together without ever draining your refrigerant.

The compressor turns just fine. I suspect its just the clutch that has failed and I strongly suspect that its the coil that failed, it's showing open loop to ground and I would expect at least some resistance there.

[DieselElectric]

Definitely should be resistance. As said above it's worth taking a close look at the wiring. Could even go as far as to remove the clutch. Worst case scenario you gotta replace it anyway.

[hoeser]

Definitely should be resistance. As said above it's worth taking a close look at the wiring. Could even go as far as to remove the clutch. Worst case scenario you gotta replace it anyway.

Took a close look at the wiring. No issues. Continuity all the way to the coil. It's the coil pack most likely. I'm gonna pull the front clip and remove the ac clutch assembly and see if I can find the whole clutch, or at the very least a coil. I've got a wanted add in the classified section.