Fan Control Module and A/C Problem

[monkeybird747]

Hello all, here are my issues.

2002 Allroad 2.7t 6MT Stage 1

Symptoms:

1. A/C started getting really warm while at idle. Ice cold when driving.
2. Started noticing the temp creeping toward 3/4 hot when idling for extended periods.
3. Haven't seen either electric cooling fan come on by itself (in front of radiator and behind on passenger side). My understanding is that the passenger side electric fan should always be on whenever the A/C is on (without ECON).
4. Hearing a lot of periodic hissing when the A/C cuts in and out at idle. About every minute or so (normal?). The hissing coincides with the a/c getting warmer.

What I tried so far:

Had A/C charged. They put in about 2 ounces. I didn't notice any difference.

Took to the local Audi indy shop. They said bad fan control unit, which coincided with what I had read in online forums. They bench-tested the electric fans and both worked with direct power. They wanted $600 to repair, so I thought I would take a shot at it. Ordered a replacement from URO Parts for $85 (mistake?).

Installation wasn't terrible. Managed to get both nuts back on and the wires back in the factory routing. However, the electric fans still don't come on. Even with A/C full cold, no econ switch, Oil temp around 225, and coolant temp 3/4 scale hot. Turning the heater on brought the temp back down. Oddly enough, even with the heater full hot, I was still hearing what sounded like the a/c compressor kick on and off, with the associated hissing sound. I also noticed my climate control tries to automatically control the fan speed when I adjust the temp, even though the AUTO mode in not selected. Not sure if this is normal for this car, or if my climate control module is going bad.

I changed the fan control switch (blue) and coolant temp sensor (green). No change.

I pulled the fan connections next to the washer reservoir and applied 12v to the two different two-pin connectors for the fans. The reddish-brown one for the fan in front of the radiator, and the black one for the passenger side fan. The fans came on. I had to give the fan in front of the radiator a gentle nudge, but it came on (maybe because I was using a pretty small jumper wire made from speaker wire?).

I used a multimeter and checked the other side of the connection coming from the fan control module, and only have around 9.8 volts d/c or so to each fan. I don't know if this is normal, or if I should have a full 12 volts. I read something about pulsing/modulated power yadda yadda yadda from the FCM, so I'm not sure what exactly I should read coming out of the FCM. I was expecting 12 volts though.

So, did i get a bad replacement from URO Parts, or is there something else I'm missing? Also, I assumed the fans not working had something to do with the A/C getting warm at idle, but could I be dealing with two separate problems?

I could use some additional insight. The only thing I can think to do is try a different FCM. I hate to drop the $215 for a new factory one, but I probably should have. Then I wouldn't be second-guessing the status of the replacement.


I await your expert tutelage, oh great forum masters!

[glennda5id]

Check wiring and grounds. Are there relays for the fans?

[glennda5id]

You replaced J293?

I guess no relays.

[glennda5id]

I would be checking ground and the 60A fuse.

[rollerton]

Check the Engine Module for errors. It will tell you if there's a problem with the fan control module. You can also run output tests with VagCom and make the fans run, either from the Engine module or possibly HVAC module. If they run w/ output test then I'd guess power supply/ relays are okay.
From my experience when the engine is warm if you run the A/C (not in Econ) then the fan should run and the A/C compressor should definitely click on any time HVAC is running and not in Ecaon mode, especially when on defrost. But I always use VagCom first, I really have no idea how you could start diagnosing without it. I can't remember specifically where they are, but there should also be a high pressure and/or temp sensor in the A/C line somewhere. That could cause A/c compressor cycling I suppose...

[monkeybird747]

Check the Engine Module for errors. It will tell you if there's a problem with the fan control module. You can also run output tests with VagCom and make the fans run, either from the Engine module or possibly HVAC module. If they run w/ output test then I'd guess power supply/ relays are okay.
From my experience when the engine is warm if you run the A/C (not in Econ) then the fan should run and the A/C compressor should definitely click on any time HVAC is running and not in Ecaon mode, especially when on defrost. But I always use VagCom first, I really have no idea how you could start diagnosing without it. I can't remember specifically where they are, but there should also be a high pressure and/or temp sensor in the A/C line somewhere. That could cause A/c compressor cycling I suppose...

I have an Xtool VAG 401. No engine fault codes. I'm not that day with some of the more in depth functions of the vagcom, but I can't seem to run any output tests for the channels related to engine cooling. I thought I read somewhere that this was not possible on this car for whatever reason. The a/c sensor is a good idea for me to check.

[monkeybird747]

I would be checking ground and the 60A fuse.

I checked the fuses under the steering wheel according to the Bentley manual. The ground is a good thought, but if it were a ground or dude error I don't think I would get any voltage at all. I'm getting 9.5 volts or so coming out of the FCM.

- - - Updated - - -

You replaced J293?

I guess no relays.

I have not and will have to will look into this.

[monkeybird747]

You replaced J293?

I guess no relays.

I thought you were talking about something else. J293 is the Fan Control Module, which I replaced with an aftermarket URO replacement. Getting 9.8 volts out of that module, and I'm assuming I should have 12 volts. I have an OEM one on order, and will update when I get it installed. I've been sidetracked with a heater core issue. Just bypassed it at firewall until winter hits Texas. Which could be quite sometime.

[rollerton]

If you can scan the HVAC module for errors give that a try. It's a long shot but I found out recently that the air-quality sensor up by the cabin filter can turn your A/C off.
Maybe try cleaning that sensor, of unplugging it or smashing it. I have no idea what it's parameters are or how it interacts with the HVAC system. I wa sunder the impression it was only somehow involved in recirculating air or something...but no... seems like it's tangled up in some other stuff that actually matters.

More likely that your fan module is at the root of the problem though, or whatever is causing your slight hot running issue.

[glennda5id]

I thought you were talking about something else. J293 is the Fan Control Module, which I replaced with an aftermarket URO replacement. Getting 9.8 volts out of that module, and I'm assuming I should have 12 volts. I have an OEM one on order, and will update when I get it installed. I've been sidetracked with a heater core issue. Just bypassed it at firewall until winter hits Texas. Which could be quite sometime.

If you are only getting 9.8 volts at the fan I would suspect a poor positive or ground connection to the module. I will take a look when I get a chance at the wiring diagrams.

[monkeybird747]

If you can scan the HVAC module for errors give that a try. It's a long shot but I found out recently that the air-quality sensor up by the cabin filter can turn your A/C off.
Maybe try cleaning that sensor, of unplugging it or smashing it. I have no idea what it's parameters are or how it interacts with the HVAC system. I wa sunder the impression it was only somehow involved in recirculating air or something...but no... seems like it's tangled up in some other stuff that actually matters.

More likely that your fan module is at the root of the problem though, or whatever is causing your slight hot running issue.

Thanks, I'll check on that sensor. I saw it had been zip-tied up by the airbox, so maybe something is going on with it.

[monkeybird747]

If you are only getting 9.8 volts at the fan I would suspect a poor positive or ground connection to the module. I will take a look when I get a chance at the wiring diagrams.

Thanks for checking, how would I go about testing the ground connection? Should I be checking the inputs to the FCM? I've only been testing the output voltage.

[rubio469]

Thanks for checking, how would I go about testing the ground connection? Should I be checking the inputs to the FCM? I've only been testing the output voltage.

I'm having the same issue as you are.. as long as I'm moving then coolant temp stays in the middle and AC blows cold.. I never see the smaller fan turn on no matter what..

[monkeybird747]

Ok, so I think I have everything fixed. Or it's at least broken in a way that is working for me. The problem? I'm not exactly sure what fixed my fans.

So on the advice of others in regards to crummy chinese URO parts, I re-replaced my fan control module with a new OEM made in Hungary. I'm getting pretty good at replacing these FCMs, so if anyone wants any tips I'm your guy! After it was replaced I started the car, turned on the A/C to max cold, made sure the econ button was off, and poof! Nothing. Still no electric fans turning. Not the passenger side one, and not the one in front of the radiator (and the car was hot). I was seriously bummed and ready to take it to a mechanic. I buttoned everything up and moved on to replacing my heater core, which turned out to only be about a 30 minute job. In the process of reinstalling the heater core I made a little nick in one or two of the wires in the giant bundle that runs next to the heater core and behind the center part of the dash. There was a small spark, and many expletives. I finished the heater core install, taped up the bundle, and pulled every single fuse out of the driver's side fuse box and visually inspected them. I had a 10a fuse blown for brake lights (#13 i think). I replaced it and chocked it up to my careless sparking during the heater core install. I started the car and turned the heat up to full blast and began bleeding the new heater core. When I was finished I turned everything back to cool and voila! Both electric fans came on and were going gangbusters. I let the car idle for a really long time and I got no overheating, the compressor didn't kick in and out every few seconds, and the a/c blew cold the entire time. This was at 90+ degrees ambient in central Texas today.

Oddly enough, now none of my driver's door lights work. No puddle light, or red entry light, or driver's footwell light. I checked all fuses. I'm baffled. They worked before I removed the kick panel. Maybe I forgot to plug something back in?

So, its still too early to tell if the fans will work correctly from here on out. However, I have a few possible reasons things may have started working, and have listed them in descending order of probability:

1. I pulled every single fuse in the fuse box during my visual inspection. Maybe, without knowing, I jogged a computer or relay or controller or something by pulling its fuse.
2. While I had the kick panel removed from beneath the steering wheel I pushed and wiggled the various relays that were within reach to make sure everything was seated correctly. I know that there is more than one relay down there in the 8-fold and 13-fold panels that has something to do with cooling fans. Maybe I wiggled the correct one?
3. When I shorted the wire whilst installing the heater core, I randomly shorted my driver's door lights to the aux cooling fans, and the door light circuit is now powering my cooling fans in perpetuity, or until something melts.
4. I actually didn't fix anything, but rather I had a heatstroke underneath the car and am actually still lying there, 10mm wrench in-hand, waiting for someone to wonder where I am. In which case I'm not actually writing this, and you're not actually reading this.
5. Plasma balls from a nearby thunderstorm jolted the fans to life.
6. The swears I uttered were in the proper sequence so as to conjure an ancient spell, thus exorcising the electrical demons plaguing my allroad.
7. Spiderman fixed it (everybody gets one).
8. Something to do with Chemtrails.
9. Microscopic thermite detonations set by the government.
10. I finally got the 1.21 gigawatts I needed to by harnessing the power of lighting and channeling it to the allroad through a piece of clothesline and the roof-mounted whip antenna.

Now, can anybody help me fix my door lights?

[glennda5id]

I ran into an issue recently with my rear wiper not working most of the time. Turned out it was due to a loose connection in the fuse panel with the fuse. I adjusted the metal contact to get a better contact with the fuse.

[monkeybird747]

I spoke too soon folks! The fans are back to not working today. I tried wiggling all the relays under the dash. Pulled and inspected all the fuses in the side panel fuse box. Tried various switch positions on the climate controls. I'm at a loss at this point, and will have to find a good audi mechanic to take it to. Totally bummed The door latch switch thing is just the icing on the cake, and might be last straw for me and this allroad. Which is a shame because I searched high and low to find this combination of 6sp manual, coil-over converted, stage one allroad.