Radiator fans not coming in !!!

[Markis236]

Right my fans are not coming in when my car starts to over heat ! It's fine when I'm driving but when in traffic the temp rockets up ! Some one will tell me it's a simple fix ? Mabel a fuse ? I have vag come and all it sayed is radatior fan malfunction

[r5gtt]

make sure the cars stones cold and hasn't been driven and see of the fans turn by hand?.

[Markis236]

Ye iv tried this both fans turn freely with no drag and don't catch any thing

[r5gtt]

Have tm you tried turning them on with vagcom?.
I think it maybe your temp sensors have failed preventing them to send the signal to the ecu which on turn switches the fan on when the car is overheating. £45 odd from the dealers as I replaced my tt one when I had this problem a few years back and all was well. Even noticed higher fuel consumption too.

 heck fuse f38 in the engine bay fuse box.

[Markis236]

This. Pups be the problem I'll check this straight away and how do you check your fans with vag com only just bought it so still a bit fresh with it haha

[r5gtt]

Yeah let us know how you get on.

Go into hvac in vagcom and then click on output test.

[Markis236]

Ok finally got home to check my fans with vag com whent on engine - out put test- fan 1 control circuit and it comes up with refused by control module ? What does that mean ?

[r5gtt]

Oh crappers  make sure you adhere to the last paragraph as I believe this to have failed.

Try this.

If you look at a wiring diagram, you will notice the ECM-(J220) does have a connection to the J293 and this is the signal wire the ECM uses to command the fan 'on', using a PWM (pulsed-width-modulated signal).

You should be able to conduct an Output Test with the ECM (key-on, engine-off). The fan should 'ramp-up' from 0 to 100% and back to 0% speed.

If the fan does not operate check the Measuring Value Block(MVB) Group 135, field 2 will show you in (%) the current fan output speed from the ECM.
MVB-137 will show you some AC system status/request info.

If the above looks okay, check the fuses:
S4(5amp) = Located on the left side of dash
S42(40/60amp) = Located above relay panel in dash

If they are okay, you will need to check the signal from the ECM to the J293, use of an oscilloscope is the preferred way. You maybe able to see some voltage on a DVOM, set to AC voltage, but that is only RMS voltage.

If there is no ECM signal, check the wiring to J293 from the ECM, should be the red/white wire.

And if you have voltage in, signal in and the fan powers-up, it sounds like the J293 has failed.

[exodus_ste]

I have this exact same problem. Carried out the output test in vagcom and the fan operates normally, just not when the engine gets hot. Oddly, when the engine is getting hot the fans come on when i switch the engine off! Be interested to hear how you get on Markis.

Some great info there r5gtt. Tell me is the J293 in the fan pack itself?

[r5gtt]

Hi @exodus_ste yes it's fitted to the left hand lower side of the pack. I also found on other cars that the temp switch on the block can cause similar issues but that's also when temp gauge doesn't reach operating tempreture. Hope all that's relevant.

cheers

[exodus_ste]

Ok so as far as im aware you cant just change the module, the fan assembly has to be changed? I hope so as ive purchased a new set. Doing an intercooler swap as soon as my peron turns up, so a good time to do it.

For the record ive changed both temp sensors when i did the stat a few months back. Helped with the car running cool under light load!

sorry for the hijack Markis but hopefully some more input will help.

[r5gtt]

This sensor can be replaced without the fan pack.

Good to know you've replaced your sensors as people don't realise these go faulty as they don't always show up on Vagcom  VAG.