[Mk2] [Turbo] Rad fans not working

Anything to do with the electrics of the car.

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markstevieandmads
Posts: 2025
Joined: Mon Aug 05, 2013 8:18 pm
Location: Swindon, Wilts

[Mk2] [Turbo] Rad fans not working

Post by markstevieandmads »

I recently replaced my rad for an alloy one and at the same time got rid of the air con as it didn't work anyway.

The car doesn't overheat but I can't get the rad fans to work. Tbh I've never noticed them working since I've had the car though it has never overheated and stays around 78 -90c according to engine readout on my android phone. Temp gauge wise it stays half way or normally just below.

Now the air con is removed (didn't have gas in it anyway) I'd expect the fans to run constantly due to the fail safe way they are wired as OEM.

I know I have to bridge the air con pressure switch but I'd have thought this would stop them running constantly and my problem is they don't work anyway.

I'm guessing to test I need to check all the rad fuses and can I bridge the temp switch to switch them on or should it be open circuit to make them run?

I could put 12v on each of the fans to make sure they turn ok but I know they are not seized as I had them off yesterday when I replaced the rad.
markstevieandmads
Posts: 2025
Joined: Mon Aug 05, 2013 8:18 pm
Location: Swindon, Wilts

Re: [Mk2] [Turbo] Rad fans not working

Post by markstevieandmads »

Quick update.

I unplugged the pressure sensor from the air con and both fans started at full speed. Strange as there is no pressure in the air con so i could only think that my air con pressure switch was faulty.
I then put a link across the pressure switch connection.
This stopped the fans.

I then disconnected the fan switch temp sensor and again the fans ran full speed.

So this proves all ok with wiring and relays.

After a little bit of searching on the web it seems the fan temp switch doesn't operate until 90c and my car was only reaching 78-80c so I'm confident that it is ok.

However, I have also wired a switch as normally closed going to open to the now unused pressure switch and mounted this down by my fog light switches so i can manually bypass the temp switch and put fans on full speed while on track if necessary and it will still work off the fan switch if i forget.
pbmr2
Posts: 929
Joined: Fri Jun 18, 2010 12:49 pm

Re: [Mk2] [Turbo] Rad fans not working

Post by pbmr2 »

the non air con cars have a bridge that plugs into the loom where the air con sensor would normally connect to. could grab one of them from a uk car being broken. Have a feeling it`s got a resistor in it.

a number of people have wired up the second fan as a manual override. could use a fog light switch if it`s a track car as they would have been removed.
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