diesel cooling fan problem

[spofforth]

I recently replaced the old 3 speed fan with a new 2 speed supplied by Jules. This new fan operates even when the air con is off, and not at a constant speed - it pulses and so sounds peculiar. At night this effects the headlight intensity, causing a slight flickering effect as the fan speed fluctuates. I am trying to contact Jules for his thoughts, but have so far been unsuccessful. Has anyone any ideas on this problem?

[T-Cut]

Definitely not right. Did you fit it yourself?

TC

[spofforth]

Yes, I did fit it myself. Electrically, there are only two connectors so I can,t think that I've done anything incorrectly.

[T-Cut]

A pulsing (on-off-on-off) type behaviour is typically due to the failure of the slow speed resistor under aircon demand. However, it seems unlikely in this case as I'd assume the fan already has an uprated resistor. (??) Does it run fast then slow, fast then slow? Is this all the time when the ignition's on? Does it stop when ignition is turned off?

Running when aircon is off (and engine not overhot) suggests a problem with a relay. If a relay sticks on, the fan will run all the time, even without the ignition on. It doesn't sound like it's doing that, so it needs more info to diagnose. Does the aircon system work normally?

TC

[spofforth]

Air-con working fine and the fan does not run when the ignition is off. I would describe the effect as the fan running fast, slow, fast etc. Uprated resistor is fitted. I let the engine idle for some time last night and eventually the pulsing stopped. The fan then did not operate on 'econ' but came in intermittently at high speed when air-con was selected.

[SD1too]

Hi Andrew,

I think you should talk to Jules about this. For a diesel engined car you need a specific fan control box containing PWM electronics. It sounds to me as if you may have the petrol version.

Simon.

[spofforth]

Many thanks Simon. I have spoken to Jules and he is on the case. I had wondered if my fan was the petrol version but I am not sufficiently clued up on these things to speak with any authority. I will report when all is sorted out.

[Jules]

Hi Andrew
Just searched my records and dispatch note says P110 on it which is Diesel.
(phew!)

If you kept the box just make sure it Says PGJ000110 under the postage label.
Keep me posted

[spofforth]

Finally sorted out. The circuit board in the fan control box was faulty, which is exactly what Jules had predicted. Replacement proceeded smoothly until I managed to refit the slam panel slightly out of alignment which caused me a frustrating hour trying to open the bonnet. All is now fine!

Again, thanks to all who commented above and particularly to Jules.