AC Quit, no fans, no compressor - '04 Golf

Hi guys,

My AC stopped working suddenly... and Oklahoma summer heat is coming...
I've read multiple threads and and have done a bit of troubleshooting this issue. I'm needing advice to help me think through this...

- My AC has blown cold and was professionally recharged about two years ago.
- When I push the AC button, the button lights up, the dash fans stay running... but no activation of AC system, no compressor, no radiator fans... nothing.
- I used a AC refill bottle gauge and showed plenty of pressure (in the red since the pump wasn't running).

I followed steps within this helpful thread... http://forums.tdiclub.com/showthread.php?t=242699 and found that my LH main rad fan is indeed inoperative. The smaller RH fan runs on the low setting when the rad thermistor plug is jumped.

- I checked the fuse box panel above the battery... no corrosion, no melted wires, no blown fuses. I've checked all applicable fuses in the cabin. All good.
- With the key and AC "on" (no rad fans running) I found there is 10.28v power going to the Compressor. I checked the continuity/resistance of the clutch coils and got 4.3ohms - within spec I believe but I couldn't hear a "click" sound (I'm at a noisy Apt Complex). How loud should the click be?
- I'm getting power at the rad thermistor plug.
- The G65 pressure sensor was replaced after I thought it was the culprit... but no change.
- I replaced the ambient temp sensor two years ago after it had fallen down into the LH wheel well and got ripped out...

Any other ideas? Any leads would be appreciated. Thanks, guys!

Hey guys,

I checked my FCM T14 plug connections this morning.

I found that I am getting 20mV at pin #9. A troubleshooting guide says 12v. I'm not sure where to find the issue here.
I got varied readings at pin #6

Any help is greatly appreciated

I have also found that my Recirculation button isn't lighting up or activating... could this be part of this issue?

Wish I could help but I'm following along as I basically have the same problem. Hit ac button, and nothing happens. I've checked all fuses and measured voltages and I'm getting 12v everywhere. Haven't checked the compressor or fan connectors yet but unless those don't get 12v, not sure what else to look for so I'm following this thread closely

The only thing I've seen online is that fan control module under the battery going bad. I'm going to the scrappers for all you can carry parts day and will just scoop up all the ac stuff and see if any sensors or module swaps will make a difference

AC powered up after I plugged in my VCDS program. I had also tinkered with more plugs around that time. I clicked the AC on and the one working rad fan came on. While I knew the AC was for some reason running, I measured pin #9 on FCM 14pin connector (T14) and got 12v. Before (while the ac was inop) I measured 20mV... Perhaps I have an intermittent ignition switch issue.

That's odd...did you do anything specific in vcds? I recently checked my plug going to compressor and only got 4.5v...i haven't checked the t4 and t14 connectors at the j293 ac module yet, but I figure it would likely be the culprit in my case as I heard these modules do go bad... When I get around to the scrappers I'll pick up a module cheap and see if în my case that solves issue

Read pages 4 onward for detailed things to check in the wiring.

http://pics3.tdiclub.com/data/517/A4_Air_Conditioning_Troubleshooting_Rev_7.pdf

2.2TDI said:

That's odd...did you do anything specific in vcds? I recently checked my plug going to compressor and only got 4.5v...i haven't checked the t4 and t14 connectors at the j293 ac module yet, but I figure it would likely be the culprit in my case as I heard these modules do go bad... When I get around to the scrappers I'll pick up a module cheap and see if în my case that solves issue

Click to expand...

I tried to log into the 08 HVAC controller and find any diagnostic codes. But I guess my '04 system isn't diagnosable that way.

I found that my radiator thermistor plug lock tab is broken and may be the cause of my trouble. The connector plug might have come loose. However, I unplugged the connector while the AC was running and found no change in the system while it was running.

jokila said:

Read pages 4 onward for detailed things to check in the wiring.

http://pics3.tdiclub.com/data/517/A4_Air_Conditioning_Troubleshooting_Rev_7.pdf

Click to expand...

I used those pages to find the voltages at T14 pin #9 the first time 20mV system inop, and 12v with the system operational.

ngolf said:

I tried to log into the 08 HVAC controller and find any diagnostic codes. But I guess my '04 system isn't diagnosable that way.
I found that my radiator thermistor plug lock tab is broken and may be the cause of my trouble. The connector plug might have come loose. However, I unplugged the connector while the AC was running and found no change in the system while it was running.

Click to expand...

Yea odd, 08 HVAC isn't avaliable on mk4s as far as I know (maybe on the climatronic ones it is)

Guys, forget OEM or aftermarket FCMs they are all junk and fail fast. Check out autocoolguy.com. they make good controllers. I selected 85Amp one.