*SOLVED* Cooling fan problem, both fan speeds work, but not while driving...

[Connor H]

My car got extremely got today and was boosting flat, come to realise the cooling fans are not kicking in. at all

The low speed works when the AC is on, all fuses are clean.

I tested the fan thermo switch plug with some wire and both high speed and low speed worked. But now im sort of stumped on what to test next and how to rule stuff out

any clues ? TIA

 

[Thai-wronghorse]

Ok seeing as you've already bypassed the fan switch and tested them for high and low speed functionality with success, at least you can rule those out which are very common to fail.
My attention would now turn to the actual fan switch and then the fan control module which also have a tendency to rot out.

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[Connor H]

Ok seeing as you've already bypassed the fan switch and tested them for high and low speed functionality with success, at least you can rule those out which are very common to fail.
My attention would now turn to the actual fan switch and then the fan control module which also have a tendency to rot out.

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Thanks for the reply T.

Ive located the fan control module under the battery, access to the plug in question was nigh impossible and ran out of time this evening. But I have a guide up for that to crack on with tomorrow.

I think ill grab a new thermo switch as they're cheap too.

Do you know if the control module controls the AC? It worked (when i tested for low speed) although i didnt leave it on long enough to check if it were cold....

 

[Gaz20VT]

It doesn't control the AC itself, only causes the fans to come on when the AC is active.

Sounds like the fan switch has died, any ideas what temps you were seeing?

 

[Connor H]

It doesn't control the AC itself, only causes the fans to come on when the AC is active.

Sounds like the fan switch has died, any ideas what temps you were seeing?

Well that hopefully rules out the control module? as the low speed fans came on with ignition ON and AC on

i kept my eye on the temps because i had a duff thermostat when i got the car, but they didnt exceed 90 that i noticed, then again i wasnt looking for small increments. Should have checked with my obd

Gonna look for the thermo switch part no and get that in asap.

 

[mty12345]

Thermo switch would be my main suspect too. Better way to test it would be to put it in hot water and use a multimeter to see if the contacts close when it reaches the right temp. Bridging it with wire would only confirm the wiring was good, not the internals of the switch.

 

[Gaz20VT]

It actually takes quite a long time for the car to reach a stage where the fans are needed. I think low speed comes on at 92 and high speed at something like 98 or 102°C.

 

[Connor H]

Thermo switch would be my main suspect too. Better way to test it would be to put it in hot water and use a multimeter to see if the contacts close when it reaches the right temp. Bridging it with wire would only confirm the wiring was good, not the internals of the switch.

Got one on order anyway as they're inexpensive. Could do with a way of testing it once ive fitted it though...

It actually takes quite a long time for the car to reach a stage where the fans are needed. I think low speed comes on at 92 and high speed at something like 98 or 102°C.

My fans used to come on, im just not sure when they stopped. The engine was basically boiling when i got home!

 

[Connor H]

Happy days the high speed fans have started working again

Shitty job but Thermo switch was the culprit

Thanks everyone she lives another day

 

[Connor H]

Got one on order anyway as they're inexpensive. Could do with a way of testing it once ive fitted it though...


My fans used to come on, im just not sure when they stopped. The engine was basically boiling when i got home!

just for info once the coolant (not engine) reaches 105 thats when my high speed fans kicked in

 

[Gaz20VT]

Was the low speed on before that?

 

[Connor H]

Was the low speed on before that?

Dont think so

 

[Gaz20VT]

Then you may have an issue with the resistors built into the fan motors. They burn out making the low speed inoperative.
When you put the air conditioning on, do you get both fans starting on a constant low speed?
I had this issue (along with the thermo switch) and managed a fix as per this thread:- https://www.seatcupra.net/forums/threads/lcr-fan-controller-radiator-fan-fault.440922/

 

[Connor H]

Then you may have an issue with the resistors built into the fan motors. They burn out making the low speed inoperative.
When you put the air conditioning on, do you get both fans starting on a constant low speed?
I had this issue (along with the thermo switch) and managed a fix as per this thread:- https://www.seatcupra.net/forums/threads/lcr-fan-controller-radiator-fan-fault.440922/

If i put my AC on the low speed fans kick in and stay on fine, whe ni bypassed the switch both low speed and high speed worked. What do you think?

 

[Gaz20VT]

Not sure, best to check it out, leave the car idling with the AC off, and get VCDS or OBD hooked up to see what happens. You can't usually hear the slow speed from inside the car, they're pretty quiet.