Fan control unit

[GomegaK]

Has anyone tried repairing the Fan Control Unit? I was thinking on removing the plastic connector and opening the lid. And then checking for loose solder connections, ect on the PCB. This module gives incidentally p1931-002.

[MikTip]

Yes....

Good luck to you!

I bought a new one.

[evolution2147]

I had that same code but it actually ended up being a bad fan. Can you confirm both your fans work?

[GomegaK]

Yes they run both. Cooling system works fine, no overheating. Only problem is that when the error occurs, coolant temp drops because of map controlled thermostat is opened by ECU.

[old guy]

Yes they run both. Cooling system works fine, no overheating. Only problem is that when the error occurs, coolant temp drops because of map controlled thermostat is opened by ECU.

You might want to do a little more trouble shooting before you replace the fan control module. The ECM runs the fans continuously and applies power to the thermostat heater when it gets incongruent readings from the sensors. Your problem could be as simple as a bad lower CTS.

[GomegaK]

Vagcom has spoken to me!

18339 - Coolant Fan Control Module (J293): Malfunction

P1931 - 002 - Lower Limit Exceeded - Intermittent.

[old guy]

Vagcom has spoken to me!

18339 - Coolant Fan Control Module (J293): Malfunction

P1931 - 002 - Lower Limit Exceeded - Intermittent.

Yes I saw that you had a P1931. but you also pointed out that both fans were still operational and that your ECM was activating the t-stat heater at the same time. I don't think a defective fan control module would cause that interaction. Your code says one thing but your symptoms are pointing to a defective temperature sensor that sends a signal to the FCM. That sensor is pretty cheap and easy to replace.

[GomegaK]

The fault occurs as follows. When driving on the highway suddenly the coolant temp drops, like the thermostat is in completely open position. This only occurs like once each month. Directly after occurrence I check the fans and both work. Switching ignition off/on, then coolant temp will return to 12:00 position after some driving. When connecting Vagcom later it shows the fault code. In my car, waterpump and thermostat are quite new. Never replaced a CTS. Wiring of the FCM seems ok. So your recommendation would be to replace lower CTS?

[Matt Devo]

The fault occurs as follows. When driving on the highway suddenly the coolant temp drops, like the thermostat is in completely open position. This only occurs like once each month. Directly after occurrence I check the fans and both work. Switching ignition off/on, then coolant temp will return to 12:00 position after some driving. When connecting Vagcom later it shows the fault code. In my car, waterpump and thermostat are quite new. Never replaced a CTS. Wiring of the FCM seems ok. So your recommendation would be to replace lower CTS?

that sounds exactly like the issue I had, though I don't remember the exact DTC (fan control module malfunction, intermittent?). I replaced the lower temp sensor without any satisfaction, so I replaced the FCM, which fixed the issue.

[old guy]

The fault occurs as follows. When driving on the highway suddenly the coolant temp drops, like the thermostat is in completely open position. This only occurs like once each month. Directly after occurrence I check the fans and both work. Switching ignition off/on, then coolant temp will return to 12:00 position after some driving. When connecting Vagcom later it shows the fault code. In my car, waterpump and thermostat are quite new. Never replaced a CTS. Wiring of the FCM seems ok. So your recommendation would be to replace lower CTS?

Your problem could very well be a bad FCM. But if you had simply posted the symptoms without adding the DTC my recommendation would be to replace the lower sensor since those symptoms are associated with a bad lower sensor. It's a $15 part that can be replaced in 15 minutes. If that doesn't fix it then go for the much more expensive FCM. You might get lucky. Unfortunately Matt didn't.

[GomegaK]

Thanks for all the information. Audizine really contains a vast amount of useful information. Which makes our lives as Audi owners a lot cheaper! I think i first have a look inside the FCM, to see if I can spot some issue.

[old guy]

Thanks for all the information. Audizine really contains a vast amount of useful information. Which makes our lives as Audi owners a lot cheaper! I think i first have a look inside the FCM, to see if I can spot some issue.

Good luck! Be sure to post up what you find as it will be beneficial for others with the same problem.

[GomegaK]

Hello All.

This is how the inside of my FCM looks like. I could not find a problem from this view. I didn't dare to take it apart any further without damaging it.
The connections looked also good to me.

[BertoG84]

Has anyone tried repairing the Fan Control Unit? I was thinking on removing the plastic connector and opening the lid. And then checking for loose solder connections, ect on the PCB. This module gives incidentally p1931-002.

Im sending mine off to module repair pro, about $100 plus shipping, ill keep you posted. They repaired my transmission control module for my cvt and fixed the problem, i thought i would have to junk the car!!!!

Getting my vdcs lite kit tom, will keep u posted with any codes I pull too, what a pain in the ass, my ecu box is dry, relay is good, and fans never come on, except when i put the key to on with out starting the car and have ac on

[coyne1981]

Im sending mine off to module repair pro, about $100 plus shipping, ill keep you posted. They repaired my transmission control module for my cvt and fixed the problem, i thought i would have to junk the car!!!!

Getting my vdcs lite kit tom, will keep u posted with any codes I pull too, what a pain in the ass, my ecu box is dry, relay is good, and fans never come on, except when i put the key to on with out starting the car and have ac on

Can you tell me how to reach the module repair pro? I just replaced my FCM and have the old one still. I'd like to try and have it fixed. Thanks!

Also, at least you didn't replace FCM, Relay, and have dry ECU box, and still fans don't work like me. Lol.

[BertoG84]

Can you tell me how to reach the module repair pro? I just replaced my FCM and have the old one still. I'd like to try and have it fixed. Thanks!

Also, at least you didn't replace FCM, Relay, and have dry ECU box, and still fans don't work like me. Lol.

lol i feel the pain, I'm also sending them my abs control module, as that is also intermittent, comes on with the esp and abs light and the brake light flashes and beeps 3 times when you start the car....too many damn modules!!!!!!

the company is based out of CA (818) 235-1095 found them on ebay for my tcm

[coyne1981]

lol i feel the pain, I'm also sending them my abs control module, as that is also intermittent, comes on with the esp and abs light and the brake light flashes and beeps 3 times when you start the car....too many damn modules!!!!!!

the company is based out of CA (818) 235-1095 found them on ebay for my tcm

Thank you very much!

[bmx672]

I've got the same problem... was wondering if it can be fixed as well, so this is a great thread for me:)
Otherwise the cheapest replacement I've found is around $350... anyone see anything better than that?
Thanks.

[coyne1981]

I've got the same problem... was wondering if it can be fixed as well, so this is a great thread for me:)
Otherwise the cheapest replacement I've found is around $350... anyone see anything better than that?
Thanks.

make sure this is the problem because i bought a new one and its still not working right. But here:

http://www.ebay.com/itm/AUDI-A4-RADI...563f85&vxp=mtr

[bmx672]

Good idea! Ill check the fuses and the actual fans before I order one!
By the way, I contacted the place in CA mentioned in this thread and they said they do not fix Audi FCM's?
I don't have any codes either btw. I thought a bad relay or fuse would give me a code, that's why I suspect the FCM.

[bmx672]

Well, turns out that both my fans are shot:( hooked both up directly to the battery and nothing!

[danidelev]

Bumping this thread since I have the same issue and I didn't want to make a new thread.

So I have the same sympthoms as the OP described, but I only get the error when it is hot outside (more than 20 degrees celsius). For the past 6-7 months I haven't had the error once.

I have done full service maintenance recently:
Water pump replaced
t-stat replaced
lower CTS replaced
new coolant

I have even replaced the fan control unit and I still get the error from time to time and the temp drops on highway. Very rear though. Both fans seem to work properly. As far as I know the big fan is controlled by the A/C and it runs most of the time. Could it be that the small fan fails from time to time and the errors pops up?

Is there any way to check whether the fans are fully operational?

[GomegaK]

Bumping this thread since I have the same issue and I didn't want to make a new thread.

So I have the same sympthoms as the OP described, but I only get the error when it is hot outside (more than 20 degrees celsius). For the past 6-7 months I haven't had the error once.

I have done full service maintenance recently:
Water pump replaced
t-stat replaced
lower CTS replaced
new coolant

I have even replaced the fan control unit and I still get the error from time to time and the temp drops on highway. Very rear though. Both fans seem to work properly. As far as I know the big fan is controlled by the A/C and it runs most of the time. Could it be that the small fan fails from time to time and the errors pops up?

Is there any way to check whether the fans are fully operational?

OP talking . Funny to see that you have the same relation to the ambient temperature as myself. The problem only occurs at high ambient temperatures. Since it did not appear again since last summer.

[danidelev]

One thing I noticed is that when the temp starts to drop if i stop, turn off the car and start it again, the temp goes back to normal in like 2 seconds and after that tehre are no issues for the rest of the travel.

[evolution2147]

Bumping this thread since I have the same issue and I didn't want to make a new thread.

So I have the same sympthoms as the OP described, but I only get the error when it is hot outside (more than 20 degrees celsius). For the past 6-7 months I haven't had the error once.

I have done full service maintenance recently:
Water pump replaced
t-stat replaced
lower CTS replaced
new coolant

I have even replaced the fan control unit and I still get the error from time to time and the temp drops on highway. Very rear though. Both fans seem to work properly. As far as I know the big fan is controlled by the A/C and it runs most of the time. Could it be that the small fan fails from time to time and the errors pops up?

Is there any way to check whether the fans are fully operational?

I'm only going to comment again because I had the same error code and I was just about to purchase a new FCM but it ended up being a defective main fan. One of the fans is quite large and the other is pretty small. On my car the small fan would constantly be on full blast and would be very loud and the bigger fan never turned on, but the car never seemed to overheat. It finally did overheat when it got to around 110 last summer. I replaced the main fan and now the FCM seems to operate them at the same time rather than independently. (I'm pretty sure that is normal because the FCM controls the speed)

If you are certain your fans are good then I would suspect a coolant temp sensor. I cannot see the FCM controlling the thermostat but I can see the ecu and FCM getting confused if a temp sensor is acting up.

[2002]

I had the same problem not too long ago and it ended up to be the coolant temperature sensor. I have an A4 B6 3.0. The sensor was just $10 and was easy to replace. Don't forget to get a new O-ring and clip. Good luck finding the problem.

[danidelev]

My fans seem to be operating correcly. The big fan is control by the A/C. When i start the car both fans are off. As soon as I turn on A/C the big fan start to spin on variable speed. The small fan is still not running. When the coolant temp reaches over 90 C the small fan kicks in until the temp is back to normal. I don't see anything suspicious there.

The only part that i haven't changed yet is the upper coolant temp sensor. Since its relatively cheap I will change it as soon as I have time.

[diagnosticator]

The fan on the right side, the smaller fan, is the A/C condenser fan and is controlled by the A/C control module in the dash. The fan on the left side, is the large radiator fan, and is controlled by the ECU by sending a fan control PWM signal to the fan control module. The A/C condenser fan runs whenever the A/C compressor is activated, in Auto or Manual mode. The A/C condenser fan does not run with the A/C system OFF or in Econ mode.
When the HVAC is in Auto mode, the condenser fan is always running in slow speed mode. In cool weather, the constant running condenser fan provides enough air flow through the radiator so that the large radiator fan practically never runs.

[danidelev]

The fan on the right side, the smaller fan, is the A/C condenser fan and is controlled by the A/C control module in the dash. The fan on the left side, is the large radiator fan, and is controlled by the ECU by sending a fan control PWM signal to the fan control module. The A/C condenser fan runs whenever the A/C compressor is activated, in Auto or Manual mode. The A/C condenser fan does not run with the A/C system OFF or in Econ mode.
When the HVAC is in Auto mode, the condenser fan is always running in slow speed mode. In cool weather, the constant running condenser fan provides enough air flow through the radiator so that the large radiator fan practically never runs.

When I'm in front of the car, looking at the engine bay, the fan on the right is controlled by the A/C and the one on the left is controlled by the ECU. Is that right? It looks to me that the one on the right is the bigger one. :D

[diagnosticator]

When I'm in front of the car, looking at the engine bay, the fan on the right is controlled by the A/C and the one on the left is controlled by the ECU. Is that right? It looks to me that the one on the right is the bigger one. :D

Left/Right references are from sitting in the driver's seat looking toward the front. Looking into the engine bay from the front, the radiator fan is the right, the A/C condenser fan is the left fan.

[coyne1981]

When I'm in front of the car, looking at the engine bay, the fan on the right is controlled by the A/C and the one on the left is controlled by the ECU. Is that right? It looks to me that the one on the right is the bigger one. :D

From the perspective you describe, yes the one on the right is the bigger one. This however, is not, or SHOULD not be controlled by the A/C. Its vice versa.

[diagnosticator]

From the perspective you describe, yes the one on the right is the bigger one. This however, is not, or SHOULD not be controlled by the A/C. Its vice versa.

The fan control module only manages the high current switching of the power supply to both fans, but the fans are primarily controlled by the ECU for the rad fan, and the HvAC controller for the condenser fan.

[GomegaK]

My fans seem to be operating correcly. The big fan is control by the A/C. When i start the car both fans are off. As soon as I turn on A/C the big fan start to spin on variable speed. The small fan is still not running. When the coolant temp reaches over 90 C the small fan kicks in until the temp is back to normal. I don't see anything suspicious there.

The only part that i haven't changed yet is the upper coolant temp sensor. Since its relatively cheap I will change it as soon as I have time.

Hello small update from my side. I did replace both Coolant temp sensors when I had to change my waterpump due to an other problem. However afterwards I still did get the error twice during my holiday trip. Then there is only one option left for me: changing the FCM. Or just live with it. Is there someone who knows a bit more about the detection mechanism that sets this error?

Error:
18339 - Coolant Fan Control Module (J293): Malfunction

P1931 - 002 - Lower Limit Exceeded - Intermittent.

Status so far
1. New thermostat
2. New waterpump
3. New both CTS
4. Fans operate fine
5. FCM wiring looks good
6. Error occurs sporadicly at higher ambient temps when driving on the highway
7. Thermostat is controlled in open position, when error is active
8. Coolant temperature drops as result
9. Ignition cycle resets issue

[danidelev]

Hello small update from my side. I did replace both Coolant temp sensors when I had to change my waterpump due to an other problem. However afterwards I still did get the error twice during my holiday trip. Then there is only one option left for me: changing the FCM. Or just live with it. Is there someone who knows a bit more about the detection mechanism that sets this error?

Error:
18339 - Coolant Fan Control Module (J293): Malfunction

P1931 - 002 - Lower Limit Exceeded - Intermittent.

Status so far
1. New thermostat
2. New waterpump
3. New both CTS
4. Fans operate fine
5. FCM wiring looks good
6. Error occurs sporadicly at higher ambient temps when driving on the highway
7. Thermostat is controlled in open position, when error is active
8. Coolant temperature drops as result
9. Ignition cycle resets issue

I have also changed everything - two temp sensors, water pump, tstat, coolant. I even changed the FCM with a used working one (supposed to be working) and still getting this annoying error from time to time in higher temps. Since I'm having two FCMs right now I'm plannig to open one of them and try to fix it. If you buy a new FCM it will be interesting to see whether it fixes the issue. Otherwise I don't see anything else that might be causing this annoying error.

Left/Right references are from sitting in the driver's seat looking toward the front. Looking into the engine bay from the front, the radiator fan is the right, the A/C condenser fan is the left fan.

So on my car the big fan on the driver's side is controlled by the A/C while the small one on the passenger's side is controlled by the ECU to cool down the engine. Could this be a regional difference since I'm in Europe, or something is not right. Could this cause the FCM to throw an error code, if the small fan is not able to cool down the engine quickly enough or something?

[diagnosticator]

Bumping this thread since I have the same issue and I didn't want to make a new thread.

So I have the same sympthoms as the OP described, but I only get the error when it is hot outside (more than 20 degrees celsius). For the past 6-7 months I haven't had the error once.

I have done full service maintenance recently:
Water pump replaced
t-stat replaced
lower CTS replaced
new coolant

I have even replaced the fan control unit and I still get the error from time to time and the temp drops on highway. Very rear though. Both fans seem to work properly. As far as I know the big fan is controlled by the A/C and it runs most of the time. Could it be that the small fan fails from time to time and the errors pops up?

Is there any way to check whether the fans are fully operational?

The fan on the left, the driver's side, is the radiator fan. The fan on the right, the passenger's side, is the A/C condenser fan. They both get power from the fan control module, but the rad fan is commanded by the ECU, and the condenser fan is commanded by the HVAC control unit in the dash.

[danidelev]

Did some testing last week and I have a few questions.

When I drive the car with the A/C turned off everything works fine. The temp sensors have correct readings, the t-stat works correctly and the the big fan on the driver's side is controlled well by the FCM. No errors. So I can exclude the temp sensors, t-stat and big fan from the list of possible faulty parts? Even the FCM works fine.

When I turn on the A/C, the small fan does not turn on at all and the "Faulty J293 module" error pops up in less than a minute. So either the fan is dead or the FCM cannot control it.
I want to apply direct 12V to the small fan to check it, but i don't really see where to apply the 12V. Is there a plug on the fan wires, which i can unplug and apply the 12V to, or I have to cut the wires from the FCM?

[GomegaK]

Did some testing last week and I have a few questions.

When I drive the car with the A/C turned off everything works fine. The temp sensors have correct readings, the t-stat works correctly and the the big fan on the driver's side is controlled well by the FCM. No errors. So I can exclude the temp sensors, t-stat and big fan from the list of possible faulty parts? Even the FCM works fine.

When I turn on the A/C, the small fan does not turn on at all and the "Faulty J293 module" error pops up in less than a minute. So either the fan is dead or the FCM cannot control it.
I want to apply direct 12V to the small fan to check it, but i don't really see where to apply the 12V. Is there a plug on the fan wires, which i can unplug and apply the 12V to, or I have to cut the wires from the FCM?

Interesting,
so your symptoms have become worse? First it was sporadic, now every time you switch on the AC. Did you manage to open up the FCM and inspect it?

[evolution2147]

Did some testing last week and I have a few questions.

When I drive the car with the A/C turned off everything works fine. The temp sensors have correct readings, the t-stat works correctly and the the big fan on the driver's side is controlled well by the FCM. No errors. So I can exclude the temp sensors, t-stat and big fan from the list of possible faulty parts? Even the FCM works fine.

When I turn on the A/C, the small fan does not turn on at all and the "Faulty J293 module" error pops up in less than a minute. So either the fan is dead or the FCM cannot control it.
I want to apply direct 12V to the small fan to check it, but i don't really see where to apply the 12V. Is there a plug on the fan wires, which i can unplug and apply the 12V to, or I have to cut the wires from the FCM?

I have an 04 a4 and an 08 rs4 and on both cars BOTH fans are activated at the same time and the fcm controls the speeds. I have never once seen either fan run independently. Also the fan duty cycles in VCDS are always just about identical, so I am pretty sure this is normal operation.

When the fan broke on my a4 I could see sparks when the fan was supposed to be on and I tried to manually move it. I also got a fan module error. I replaced the fan over a year ago and no more issues.

[danidelev]

Interesting,
so your symptoms have become worse? First it was sporadic, now every time you switch on the AC. Did you manage to open up the FCM and inspect it?

This is becuase I'm looking at VCDS and I can see when the error pops up.
Before I was looking only at the temp readings on the dash. So when the error pops up the temp starts do drop but the gauge on the dash won't move from 90 degrees and you won't notice an issue.
The gauge on the dash goes to 90 degrees while the temp sensor readings are between around 80 - 100 degrees. If I'm driving in town and the temp drops to 80 + degrees the dash shows 90 and i don't see the error. Then on the highway the temp drops below 80 degrees because of the increased airflow and then i notice the issue.

Yes, I dissambled the FCM and it looks as good as new. If the small fan motor work well when I apply 12V to it, I will send the FCM to an electrician to check it ot.

I have an 04 a4 and an 08 rs4 and on both cars BOTH fans are activated at the same time and the fcm controls the speeds. I have never once seen either fan run independently. Also the fan duty cycles in VCDS are always just about identical, so I am pretty sure this is normal operation.

When the fan broke on my a4 I could see sparks when the fan was supposed to be on and I tried to manually move it. I also got a fan module error. I replaced the fan over a year ago and no more issues.

In VCDS on channel 135 I can see duty cycle only for Fan 1 (the big one) and everything seems normal. Do you see Fan 2 (small fan) duty cycle right next to Fan 1 ? Looks like the small fan does not exists at all in the system while it is physically there. :D

The output test also moves only Fan 1.The FCM controls Fan 1 as it should be.

First thing during the weekend will be to check the small fan with direct voltage applied to it.

[danidelev]

Finally fixed my problem.

It turned out to be the A/C fan. It was running from time to time and this is why I was getting the Intermittent error. Until it stopped working. I replaced the fan and now everything is back to normal.

How-to-test-Radiator-Fan-Control-Module - This is very informative thread about how to test the FCM.