another cooling fan question.

[xamtex]

my fan has not been working for a while now,i discovered this when the wife said the a/c was not working.
i had to change the altenator this week so opted to pull the front off to do it so i could check the fan out.
the fan itself is ok,when i do the test with the auto on there is a buzzing noise from the top relay in the box so im guessing this is at fault?
if i bridge the 2 terminals in the bottom relay i get fast fan,the 2 top terminals gives me slow speed.
can you get the top relay,or do i need to find a good replacment control box complete?...does anyone have one?

i have a picture but it seems im not allowed attachments.

[Arctic]

Hi Peter.
Do you know if you have a four wire 3 speed fan or a two wire 2 speed fan with a silver resistor, if the later it may only need the silver resistor upgrading to a Gold one.

If you have a four wire 3 speed it could be the PCB board that as failed, did you do the demist test and see if the fan runs continually or not, touching the 2 terminals maybe giving you the medium speed which you think is the slow speed.

[SD1too]

Originally Posted by xamtex

... if i bridge the 2 terminals in the bottom relay i get fast fan,the 2 top terminals gives me slow speed.

Hello Peter,

As you don't mention a third relay I am assuming that your car has a 2 speed fan system. If so, the above test seems to suggest that the motor and resistor are working correctly. The fault is very unlikely to be the relay. As you have a diesel the prime suspect is the printed circuit board which is too clever for its own good. To rule out the relay, I'd suggest removing it and testing it directly across your battery. I bet it doesn't buzz then!

Simon

[xamtex]

there is no resistor on my fan,its a deisel. there is a large relay at the bottom of the box and a small relay at the top,its the top relay that buzzes.

[Arctic]

Hi Peter.
The same as these below yes, if so can you please make sure all the A/C is off, turn the ignition to II then press the demist button I am presuming the fan is still connected to your car, does the fan run continually ?

[xamtex]

this is mine.the fan does not run at all with the demist on,if i bridge either pair of thick wires on the relays the fan runs,during the demist test the small relay buzzes?

[Arctic]

Originally Posted by xamtex

Hi Peter.
if that is your control box for your car which is a diesel then it is never going to work, as that control box is for a petrol car, diesel control boxes must have a PCB board as in the photo's i added above.

[xamtex]

its been working for about 2 years since i bought the car,its only recently its stopped working?

[SD1too]

Peter,

Thanks for posting that photograph. I'm afraid bodger man has been at work on your car. Arctic is right; your fan can never work properly with that control box. The blue/red wire carries a PWM (Pulse width modulated) signal which has been incorrectly wired to the low speed relay coil. I doubt that your air conditioning condenser has ever been cooled satisfactorily with that set-up.

What you need is a diesel control box or, at the very least, a PCB to fit to what you currently have. Arctic carries some spares and knows what he is talking about so please contact him by PM.

By the way, diesels can have 2 or 3 speed fans.

Simon

[Arctic]

Hi Peter.
I don't know how the fan as been working, some wiring bodge must have gone on, it maybe a good idea to remove the fan from the car altogether and check all it wiring, take photo's and post them up.

Below is your fan photo that you posted up above turned round.
1

Check it against this control box from a 1.8 petrol engine.
2

If your diesel car had a two speed fan with resistor the control box would look like this.
3

Or even like this
4

I note your car is a 2002 model so I would say the correct fan when it left the factory would have been this one below, four wire 3 speed fan.
5