Overheating....fan not working

[J5H VW]

Guys,

My air con compressor finally gave up the ghost and no longer runs at all....and I think that is what has caused the next issue that I experienced when stuck in traffic yesterday - overheating!

The car never goes above 90'C normally, however yesterday, it hit 125'c and was still climbing when i was stuck in traffic.  In a brown pants moment, I put the heating on max temp, highest fan speed and opened all the windows in an attempt to get rid of some of the heat.  It worked and slowly but surely, temp dropped back to 90'C.

When i got home, I checked out the fans in the engine bay - they are not running, and dont kick in even above 90'C.

I think this is liked to the compressor fault (or another issue) that might be causing this.  Can anyone advise?

Is there a way to force fans to be on all the time? (as a temporary fix).

It only seems to over heat when standing in traffiic for more than about 5/10 mins - on the move its on, guess its due to the airflow into the engine bay when moving.

Is there a fuse or anything that I might need to check?

[Rhyso]

in all honesty apart from your air con not working you could have a knackered water pump 

[J5H VW]

Anyway to test for that?

also, i figure that it even if the pump has packed up, the fans should still kick in right?  And they are not doing so....

[neg]

If you have the air con compressor on then the fans should work at slow speed all the time - if this is not the case either then it does sound like they are cream crackered.

Check fuses, somehow check fans work at all(?), check slow speed (if you have air con)

[J5H VW]

I know the fans should work at slow speed with air con on, but when I switch it on they dont run at all.  However, I since the compressor does not kick in (as its now packed up), I am not sure if that is what is causing the fans not to work.

Basically, I am wondering if the fans are not working at all since the air con compressor has failed.

Does anyone know of a way to check if the fans are working without having to use the air con compressor?

Is there anyway to overiding the thermostat so that the fans run all the time when the car is on?  If I could do that, I guess that proves the fans themself are ok.

[T_J_G]

I know the fans should work at slow speed with air con on, but when I switch it on they dont run at all.  However, I since the compressor does not kick in (as its now packed up), I am not sure if that is what is causing the fans not to work.

Basically, I am wondering if the fans are not working at all since the air con compressor has failed.

Does anyone know of a way to check if the fans are working without having to use the air con compressor?

Is there anyway to overiding the thermostat so that the fans run all the time when the car is on?  If I could do that, I guess that proves the fans themself are ok.

On a MK2 if you supplied them with power they'd spin..

[neg]

Fan control unit is under the battery I think - somewhere around there, if you could find the main feed I am sure you could then test them.

Not a coolant sensor problem is it..?  Not working so not reporting the temp to kick in the fans..? just a thought.

[Krust_GTI]

in all honesty apart from your air con not working you could have a knackered water pump 

good shout, thats what happened to me

[J5H VW]

Fan control unit is under the battery I think - somewhere around there, if you could find the main feed I am sure you could then test them.

Not a coolant sensor problem is it..?  Not working so not reporting the temp to kick in the fans..? just a thought.

I dont think thats it, as the temp guage still works (and seems to behave as i would expect it to).

[M4VERICK]

I know very very little about cars, but i thought id offer what happened to my old Astra as a possible cause.  Basically, the car was overheating and the fan wasnt coming on.  The cause was a radiator switch which clicks the fan on when the water in the radiator hits a certain temp. 
Could that be it??