Rad fan not working

[STEWY L]

the control units fail on a regular basis, all part of the fan motor etc. i believe
quite common from what i have read
regards,
stewy.

[engfour]

I had problems with the cooling fans on all my TDIs. In every case it has been the fans at fault. I have bought replacements from GSF which have been fine and much cheaper than the dealers. The fans have two speeds. They run on high speed when the A/C is turned on and on low speed when the temp in the rad gets hot. There is a rad sensor on the side of the rad. Both fans are controlled by a fan controller relay module location below the battery mounted on the chassis rail. The wiring from the fans plugs in to this control box.

The fans never run much to keep the engine cool. They only seem to run when the car is stationary in hot weather. The first time I discovered I had a problems was when I was parked on the M25, 25 deg C and had the A/C on. Temp gauge went in to the red! Turned the A/C off and the heater on and with in seconds temp was back to normal. Another time I realised the A/C did not cool very well when I was stationary but was ice cold when I was doing 70mph on the motorway.

I remove the fan and bench test it with a 12voly supply. You can test it on both speeds. I have only ever changed the rad switch when rad needed replaced as the system was drained down anyway.

hope this helps

[vw_prince]

I had problems with the cooling fans on all my TDIs. In every case it has been the fans at fault. I have bought replacements from GSF which have been fine and much cheaper than the dealers. The fans have two speeds. They run on high speed when the A/C is turned on and on low speed when the temp in the rad gets hot. There is a rad sensor on the side of the rad. Both fans are controlled by a fan controller relay module location below the battery mounted on the chassis rail. The wiring from the fans plugs in to this control box.

The fans never run much to keep the engine cool. They only seem to run when the car is stationary in hot weather. The first time I discovered I had a problems was when I was parked on the M25, 25 deg C and had the A/C on. Temp gauge went in to the red! Turned the A/C off and the heater on and with in seconds temp was back to normal. Another time I realised the A/C did not cool very well when I was stationary but was ice cold when I was doing 70mph on the motorway.

I remove the fan and bench test it with a 12voly supply. You can test it on both speeds. I have only ever changed the rad switch when rad needed replaced as the system was drained down anyway.

hope this helps

Thanks for your help, would you say take my chances on changing the fan? or the relay (on side of battery).

how do you test it on both speeds, my unc (car expert) tested it with wire it came on and whrn you put a/c on it works does that mean its working fin on both speeds.

[jonathanfenton]

The fans have two speeds. They run on high speed when the A/C is turned on and on low speed when the temp in the rad gets hot.

Sorry to doubt you but i am 99% sure you have the wrong way round. They run on the low speed all the time when the a/c is on hence why the resister inside the moters always burns out on them... forgive me if i am wrong but that is how they work on my car?

[jonathanfenton]

Thanks for your help, would you say take my chances on changing the fan? or the relay (on side of battery).

how do you test it on both speeds, my unc (car expert) tested it with wire it came on and whrn you put a/c on it works does that mean its working fin on both speeds.

The fan connector has 3 wires. two lives and one neautral. I forget the colour combos but the larger browner wire is your neautral. Wack a 12 battery on the end of it and one of your lives is for slow and one is for fast. The slow usually failes due to the resister breaking or the brush houesing needing greesing up a little bit. There are how to guides on the net somewhere. I plugged my VAGcom onto my car and i left it idleing for hours and it only managed to get to 92.5oC. I have it on good merit that they switch on at 95oC. But obviously with a/c on they are on 24/7! They only step up to high when your car gets really hot! if you have your ac on anyways the fans are always drawing air threw the radiator so permanently keeping it cool... It would have to be a seriously hot day with your aircon switched off and sat in traffic for a while for it to ever need full speed fans...

[talesy]

The water pump can be a common problem as well. Run engine to get water temperature up then Turn on the Fan to Full Blowing and then turn to Max Temperature. If your car doesn't heat up then you will no water circulating e.g water pump or thermostat usually. Since you have changed the thermostat, you can rule that out.