Car radiator Fan

**nathan2911** · 10th August 2004

I'm having problems with my car radiator fan. The temp gauge gets really high and the fan doesn't turn on. I've checked the fuse, change the thermoswitch and i know the fan works as i wired straight to the battery to check it. Anyone have any ideas what might be up with it?:nowords:

**rfcrangers** · 10th August 2004

depending on what type of car it is it is.It honestly could be a numbe rof things i e temp switch,head gadsget,air lock honestly with a bit more info i could help you.

regards

**nathan2911** · 10th August 2004

well it's a 1990 vw jetta 1.6. What other information do you need?

**TGGranada** · 28th September 2004

I know this was posted a while back, but I just saw it.

Not sure about the Jetta specifically, but the fan circuit is usually fairly simple.
Have you tried bypassing the thermo switch at its connector ? If there is a wiring fault, the switch might be operating, but the fan won't get switched on if there is a break in the wires.
Also, might be worth checking to see if there is power at the fan. Most thermo swiches switch the earth (negative) side of the fan motor, so there should be +12V to the fan whenever the ignition is on. On some cars the fan will run when the ignition is off, so these will have +12V to the motor all the time. Although you checked the fuse, there could be a broken wire or bad connection from the fuse to the fan motor.
If you have a wiring diagram, you could check to see if there is a relay in the fan circuit. If there is a relay, this could be faulty (quite a common fault on Rover 800 models - not sure about the Jetta).
One other thing. There might be a resistor in the circuit if the fan has a fast and slow speed. If the thermo switch has only two terminals, the fan probably has a single speed. If there are three terminals, the fan will usually have a resistor that gives a slow speed at one temperature, and then bypasses the resistor to give full speed if the engine gets hotter. As you say the engine gets very hot and the fan still does not cut in, this is unlikely to be the problem on your car, as the fan should still run at full speed when the resistor gets bypassed.

HTH

**the.insane** · 29th September 2004

it could ba a number of problems, the strangest ones i have found were, a faulty Temperature gauge, and a faulty water pump,

Also check that the thermostat isnt jammed in the closed position :nowords: