Fan not turning on

[rayray086]

Hey all,

My radiator fans aren't turning on like they should. The coolant temp would hit 100 degrees (middle mark is at 90 degrees) but the fans stay idle. The coolant warning light didn't flash but I turned the car off in case any damage occurs if I left it running for longer. What are some of the things that I can check? All wiring has been connected up like they should (triple-checked).

[Lorenz]

The fan switch that sits next to the radiator can be faulty. I had the same issues as your having and it ended up being that. $20 part and a very large socket will fix it up
Look like this:

[bolo]

Did you recently drain the radiator fluid? If so you need to open the air release valve and keep topping up. Otherwise the usual things to check, thermostat, thermo fan switch, fuses and possibly radiator.

[whiteVR6]

The fan switch that sits next to the radiator can be faulty. I had the same issues as your having and it ended up being that. $20 part and a very large socket will fix it up
Look like this:

If you turn your a/c on and the fans come on then this could be the issue
Also it could be the fans themselves or the fan ecu.

[badgerboards]

I did a coolant flush and water got into the fan control module which cause the fans to never turn off drained my battery. Waiting for the new module part still but now they don't turn on. Which could be the thermostat. I hope my problems help you out is diagnosing yours

[rayray086]

I did recently drain my coolant. As for the air release valve, where is that located? What I usually do is massage the top radiator hose to push out any trapped air pockets, and top up as needed.

Is there a way to test to see if the fans are actually working?

[Golf Loon]

Unplug the fan switch wiring. You should have a fat red wire and two others. With a short piece of wire, jumper from the red wire to the other 2 terminals in turn. You should be able to make the high and low speed fans come on.

If the fans turn on with the jumper wire, either the switch is faulty or not immersed in water.

To fill the cooling system, take the lid off the expansion bottle and fill it over the max mark right to the top. When the level has settled, put the lid on and warm the car up to temp. Then let it cool down and then repeat the process, untill the level settles on the max mark. the cap is a bleeder and will let the air out for you.

Hopefully fans will then come on.

You can also turn them of through the ac circuit if you turn it on inside the car, fans should come on.

Hope that helps.

[rayray086]

Thanks Matt Will try it out.

[bolo]

Using the cap from the coolant bottle didn't work for me when I did it, I still had a lot of trapped air and the coolant just wouldn't go down. Look for the top radiator hose going away from the radiator and it'll lead to a junction. At that junction there's a round piece of black plastic with a pin going through it to hold it in place. Pull the pin, then pull the round plastic. Start the car then keep topping up the liquid in the radiator ball until it comes through the air release, then close it off again.

[halvonator]

If you turn your a/c on and the fans come on then this could be the issue
Also it could be the fans themselves or the fan ecu.

My MK3 Golf has this exact problem and i've tested the fan, jumped it at the sensor, I know that the fan works because this happens to me: Whenever I turn on my A/C the fans come on. So how can I fix it?? Help is much appreciated! (so far I just put a wire right from the rad sensor straight to the fan and that works, but just for high speed)