Teutonix

Driving back from the beach on Saturday, we noticed that the A/C was starting to cycle off in traffic, and the coolant temp was rising slightly above the center point. Eventually, as traffic got heavier, the temp continued to rise... We opened the windows, cranked up the heater, and were able to keep the temp to the first bar above normal until traffic cleared... No big deal. Once we were back at full highway speed, the coolant temp went back to normal, and A/C function returned. This tells me we have a cooling fan issue.

Back home, I pulled the codes and got:

18339

P1931 002 Coolant Fan Control Module-J293 Malfunction Intermittent


OK... so we've got a fan control module issue. Searching the forum archives, I see that many people (both B6 and C5 3.0 cars) have replaced the module in response to this code, and not resolved the issue without also replacing the fans. I noticed that in many cases, one or both fans would not function at all. Since I don't feel like throwing $300 parts at the car, I want to dig a little deeper.

Here's the kicker: Both of the fans on my car are constantly on at a low speed. Sometimes when the car warms up, they will cycle to high speed for a second and go back and forth between low and high, but they never actually run at high speed. As a result, the radiator & A/C condenser don't get sufficient cooling in traffic.

Since both of the fans seem to actually be functioning, I'm leaning toward the fan control unit itself, but I wanted to see if anyone else has gone through this before.

I have seen the tech section write up on the 2.7t (and used it on my Allroad), but the 3.0 is a different animal. I've also seen the control unit replacement procedure, but the actual diagnosis does not seem to be well-defined.


Thanks!

2.7Lturbo

your diagnosis of fan control unit seems to be correct, what you should do is find the pinout on the fan for high and low speed and hook up a 12v source and see if ti will power in both high and low. if it does work on both high and low with direct power the issue is the FCU, back in the day in my jetta i just jumped the pins so the fan ran at full speed all the time, but that was a beater car i dont recommend it

Teutonix

Thanks for the response...

That was my next step. Unfortunately on the 3.0, the wires have permanent connections from the control unit directly to the fans (no plugs), so I'll have to cut/strip the wires just to test them.

Since the fans seem to be capable of running at high speed, and both run all the time at low speed, the issue seems to be on the control/regulation side.

Danomatic93

Let us know what you find!! I have a very similar issue going on right now. Just I haven't observed my fan yet. I'll have to take a look myself.

eejimm

One thing to be aware of - there are no "hi" and "low" fan connections - the control module uses PWM (Pulse Width Modulation) to control the fan speeds. So if the fans will run at high speed under 12V, and the bearings don't feel or sound bad, then the control module is the only thing left to be at fault. If all the connectors to the module are OK, and all the wires are intact (a shorted wire in the cable harness can cause the module to think it's an intermittant failure) then you are indeed left with replacing the module.
Jim

2.7Lturbo

WOW, they've come a long way adding PWM to automotive cooling fans! lol, yeah shorting pins will do nothing at this point then :/

that being said its easier now to tell if the controller is broken, if the fan was broken it would just stop working as there is not a separate setting for high and low, its just a high speed fan throttled for low control, this would place the fault squarely in the realm of the fan control module

Teutonix

Well, I ordered the control module. Everything was pointing to it being at fault, but I needed a sanity check, so thanks for that.

I will post a follow-up next week when I get it installed, just to close the loop. I can't stand it when I find a thread that explains my problem precisely, then gives a possible solution with no outcome!

Worldwidebeagle

dealing with a similar problem on my allroad. Fan Module was replaced a year ago because both aux fans stopped, and all was fine. Now ac is now cutting off when not moving. Temp gauge fine. inner aux fan does not move. outer fan cycles normally. I was told to first replace the auxiliary fan switch and that they fail as often as the coolant temp sensors. I have one on order. I guess it's summer.

Peter

Teutonix

I went through the same thing on my AR, with similar symptoms. On mine, the inner electric fan would run without issue when I first started the car, but when the car was warm, it would not....

My solution was to replace the fan, as the motor had a conditional failure - only when it was hot. (which is a terrible failure mode for a cooling fan!) It's been about 2 years since then, and all has been great. I recommend sourcing a replacement electric fan. I bought a used one from audis4parts.com

uglyfatjoe

2003 A6 4.2L.

Similar problem - Car running very warm in stop and go traffic. AC also blows warm in hot weather during normal city driving. Once I get up to highway speeds the coolant temp drops back to normal and the A/C blows nice and cold.

Both the aux cooling fan and the A/C condenser cooling fare not turning on.

I am not pulling any codes regarding the cooling system.

Does the fan control module run both fans or is their separate engine coolant temperature sensor input to the module(s) that could be faulty?