Conor Curtin

Hi everyone, my a3 is having some issues with both rad fans as well as the blower. I can't get any of them to turn on normally. The rad fans turned on for a second a couple of days ago, but aren't responding anymore. I've tested the plug for the fans, and power is being sent to 2 of the wires when the key is in the on position. I sent power to both of the fans off of the car and they both turned on. I also tested the temp sensor on the lower radiator hose and the red wire is getting power. I have tried swapping both the fans and that front temp sensor and nothing has worked. I tried disconnecting the battery to see if it would reset anything, but it didn't help. It is a brand new battery. On the dash I have the service light, esp, slippery road looking one, the wheel one, and abs. Also, the temp gauge isn't reading correctly. I realised this cause the motor overheated and popped one of the rad hoses off the front of the block and leaked out the coolant. The blower fan keeps defaulting to the lowest setting. I don't have access to vcds, or I would have checked these lights already. Anyone have any suggestions of things to test?

habbyguy

Are you sure that you got the air out of the system after you refilled it with coolant? Air in the system can cause the sensors to not read correctly, and most of the issues you're experiencing. FWIW, the fan will default to a low setting until the coolant temperature is high enough to no longer just blow cold air around, so that could be normal.

Do the radiator fans come on when you turn on the A/C? I believe (but am not sure - I'm a newbie with the Audi) that the fans should come on when the A/C is turned on.

Might be informative to know why the car overheated.

Conor Curtin

I'm not positive that I got all of the air out of the system, but the reservoir level hasn't dropped at all while the motor is running and bubbles aren't coming out in the reservoir. I have ran the engine to 95C 4 or 5 times in the last few days and it isn't losing anything.

None of the fans kick on when I turn on the ac not even the interior blower

habbyguy

It sure sounds like an electrical / module problem.

Here's what the manual has to say (this is the manual for my 2005 A3):
3 - Radiator fan - V7❑ The request for activation of the radiator fan(s) - V7- is transmitted by the operating and display unit, Climatronic control unit - J255- or by the air conditioning system control unit - J301via the data bus to the engine control unit. The engine control unit then actuates the fan(s) directly or by way of the radiator fan control unit - J293- ⇒ "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051 (for the engine control unit) and ⇒ Current flow diagrams, Electrical fault finding and Fitting locations.

The fan should come on with the A/C - either immediately, or when the system reaches a minimal pressure (which should happen right away).

Of course, check the relevant fuses (listed as fuse 3 on holder A, and fuse 38 on holder B).

The fans are controlled by the small box on the lower left corner of the fan housing - it gets power (check that) and then digital info from the computer, so it's a bit fiddly to check. This is one of those cases where you need the VAGCOM system to look into the operation of the systems more in depth.

Conor Curtin

I have checked all of the fuses in box a, as well as the blower fuses in box b.
The tfsi cars don't have a fan controller next to the radiator, unfortunately. I know the older 8p's do but not these ones. I don't know where the fan controller in this model is. I haven't been able to locate it.
I figured i'd need vag-com. Do you know where I can get it for not insanely expensive? I'm working on a tight budget.

habbyguy

I thought that might be the case (Audi seems to like to change things a LOT from year to year, or "just because"). My manual is supposed to cover just my 2006, so not much I can do to help, other than to suggest physically tracing the wires from the fan motor back to something that "should be the fan controller" (if it is still a separate module).

I'm still getting back into the VAG world - I had a rosstech dongle when I had my Jetta turbo wagon, but sold it off years ago while I took a trip through Volvoville and Acuraland. ;-) I haven't broken down and bought my VAG tool yet, but will be doing that research before TOO long (hate to not have it when I need it). FWIW, I do get a lot of info off my Torque Pro app (but that won't help you trace down the controller / toggle it on and off, but might let you see something going on with the temperature sensors.

Good luck!