Fans kicking in at 110 degrees

[Ricardo]

I have recently had a thermostat changed and the water pump was done a year or so ago. Thanks to the M1 traffic jams over the last few days when Im sat there the car is overheating and the fans are not kicking in until 110 degrees so I am sat there papping myself thinking I will be stranded in a steaming broken car. I dont like it. Having to stick the blowers on high to loose some hot air.

Is there another sensor telling them when to come on? could it be the new stat/cts? or is it time to replace the fans. Ive got a baby on the way and am hoping its not the fans as babies apparently cost bucks?

Cheers guys and what should you pay for a new set of fans anyone whos had it done.

 

[Mandip]

Sounds like the slow speed resistors on your fans have failed. This is a common fault with these cars.

A good way to confirm this is by sticking your Air Con on and having a look at the fans as they should spin slowly as soon as you switch the AC on. Also make sure the outside temp is over 5 degrees C, as the AC compressor doesn't come on if it's too cold outside.

If this is the case then you have two options, there is a mod where you can wire in an external module that controls the speed of the fans, do a search on here for that. I thought about but it seemed to fiddley for me.

Or bite the bullet and change the fans, this is what I did and it wasn't cheap. The fans cost roughly £150 each and then a couple of hours labour as the bumper needs to come off. Stealers quoted me £550 all in but I took it to a local garage and they did for £350 which wasn't too bad.

Also make sure you get the genuine vw fans as some people have had issues with the cheaper pattern parts as the fans aren't balanced properly which leads to excessive vibration when they come on.

Hope that helps.

 

[Ricardo]

Thanks that really helps, cheers for taking the time to put all the info down for me. I will check the fans, I think your right though so will get it booked in.

 

[BoomhaueR]

Sounds like the same problem I have with slow speed fans gone.
I tried this resistor kit fix but it didn't work. Kept blowing a fuse and couldn't work out why.
But this has reminded me I need to buy some new fans before the summer, which I would advise you to do the same too despite the large cost .

 

[Muttley]

The radiator fans have a completely separate temperature sensor, which sits in the radiator itself. On non-aircon cars it runs the fans on its own, without any reference to the ECU or engine sensors. It's a two-stage thermoswitch, triggering off the temperature in the radiators, not the engine.

It could be shot, and is quite easy to test or replace, if you're prepared to loose some coolant.

In cars with airconditioning, there is a control module that combines the thermoswitch actions with a signal from the ECU saying that the air conditioning compressor's been switched on and could you run the fans slowly so the condensor gets some airflow please? This module sits under the battery tray, and may need replacing, if you're out of luck.

The fans should come on at low speed as soon as you press the "snowflake" button on the heater panel or Climatronic unit (which engages the compressor to run the air cooling). If they don't then the usual failure is the high power resistors that reduce the power to the fans so as to run them slowly. High speed fans still work in that case, though. Fans can be tested by applying 12V to them....

 

[Ricardo]

Thanks for all your help guys

 

[Ricardo]

okeedokee went to London on Saturday and got stuck in traffic (suprise), it overheats and both fans go on but cant keep the tem down at 90. When you turn the aircon on nothing happens at all (with the fans). Sounds like the description above. I guess this means I have to replace the fans as a an entire unit?

 

[Ricardo]

Whoop whoop, was the control unit under the battery so not as expensive as I thought, god bless the boys at Total VAG

 

[Mandip]

Nice one glad you got it sorted.

TotalVAG are wicked I use them too! Do you live near Milton Keynes then?

 

[Ricardo]

yep in MIlton Keynes, love the drive down the new bypass to get to them