Hi all. My fans have not worked since I owned the car - 6 months. I've done a number of tests - powered up the fans directly (they run) jumpered pin 1 to pin 2 on the temperature sender (runs at low speed) jumpered pin 2 to pin 3 with ignition on - does NOT run at high speed. The fans are not running at all, ac on, ac off (note here - the ac doesn't work either - clutch isn't engaging). Could this be the fan control module that is needing replacement? Any help would be greatly appreciated. And, yes, the fuses have been checked - 40amp, 30 amp in the engine bay and fuse 16 in the cabin. Mk4 Gti 2.0 2002
If your AC gas is low, or the pressure sensor is dodgy, the AC won't switch on the compressor or fan. Sounds like control module alright.
This is usually the problem on a MK4 based vehicle. I have the this experience on my 8L S3 and our Bora VR5. The terminals under the arrowed green fuse S179, burn out and corrode, stopping AC clutch and fan circuit and I believe another consumable. This is common on vehicles with climate control that are continuously on. Solution is to tap off from S162 as per the green line. On some models S162 is free and not used.
Toyotec, the fuse you are referring to is in good order - when I jump the fans from the temp control switch they run - when I remove that fuse, they stop... Tristan, would the fans not run at all if the gas is low? Or would they at least run when the motor was on its way to over heating?
Toytec, when I jump the fans using pin 1&2 at the temp control switch, the fans run. If I pull that fuse out of the hold while the fans are running, they stop...
check the pins on your 10/14 pin plug on the fan control module, make sure the terminals ara all clean. It should have an ignition live to the black/blue wire fed from fuse 5, a permanent live on the red/grey wire fed from fuse 16 and the brown/black is the earth. If its a 14 pin plug ignition is to pin 9, live to pin 4 and earth to pin 6. The fast speed trigger from the fan switch goes to pin 7 if you wanted to check that for continuity
Thanks for that Rubjonny. Just checked all of those, and all are good. Also jumpered 30a to 2 on fan side of the FCM - fans run on high. All terminals are clean. How do I go about checking the continuity of pin 7?
Tristan, mine doesn't run at all - up to temp or not. Then again, I'm not quite sure that it is reaching true temp - gauge goes up to 90, but doesn't go over, no matter how much I rev the motor..
if you loop a wire between the live and high speed pins on the switch, you should then see 12v on pin 7
The guage shows 90 when actual temp is between 80 and 105 (those numbers might be slightly out - going from memory). You need to use vcds to read actual temperature
yep thats the one, so red to red/yellow on the radiator thermoswitch should get you 12v at the FCM pin 7. The slow speed is fed by the switch on the rad so thats why jumping the red to the red/white gets the fan on slow. for the fast speed the thermoswitch is wired to the fan control module rather than the fans, the load is too high for the switch. so when shorted the module should see this then trigger the fast speed. the fcm basically operating as a relay in this case, the power input is one of the fat wires on the battery fusebox, output to fans, live trigger from thermoswitch and earth to the brown/black. if that makes sense? I believe the fast speed only works with ignition on which is why I listed the ignition wire as well to check
this assumes it has the 14 pin plug and not a 10 pin, pretty sure by 02 they are all 14 pin but worth checking!
Right, got 12 volts there... AC clutch works too, just fed a live feed in to that. So where to from here??
