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Old 9th October 2018, 19:52   #1
rusty metal
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Default cooling fan

2002 cdt deisel est hi guys my 2 wire cooling fan is playing up it only works with ac on any ideas ? i think its proberly a relay.

regards rusty
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Old 9th October 2018, 20:26   #2
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That's the correct operation, the fan wont run until the engine overheats, which on a diesel is highly unlikely.
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Old 9th October 2018, 21:43   #3
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no its not correct i know the way is should be i've owned it since it was 3 years old [13 years] the car starts to over heat and the fan dont come in till i turn the ac on then cools down instanly

Last edited by rusty metal; 10th October 2018 at 07:38..
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Old 9th October 2018, 23:07   #4
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I'm sorry to disagree but Andy is correct, on every single diesel we've seen (which must be in the 1000's) the fan runs when the Aircon is set to Auto.

It will start to run as soon as the ignition is turned on and aircon set to auto even when the engine is cold. That's the way it's designed

Take a look here: https://www.the75andztclub.co.uk/for...ead.php?t=1371

If your car is overheating (which in normal running just doesn't happen, even with a non working fan) then there's a distinct possibilty that there is a problem with the coolant circulation.

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Old 9th October 2018, 23:12   #5
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Quote:
Quote:
Originally Posted by rusty metal View Post
no its not correct i know the way is should be i've owned it since it was 3 years old [13 years] the car starts to over heat and the fan dont come in till i turn the ac on then cools down instanly
Hi Frank.
If your diesel car is over heating then there is something else wrong, as I/we have never heard of a diesel over heating, have you used the OBD to check the real temperature of the engine, No19 then No7 let the car tick over and wait to see what temperature the engine gets to be for the fan kicks in.

Before that make sure all the A/C is off, turn ignition to II and press the demist button, look through the front grill is the cooling fan running continually or not running at all.

Also can you see a silver resistor at 2.oclock through the front behind the fan blades.

Report back to us.

PS Russ is faster at typing me thinks.


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Old 10th October 2018, 07:41   #6
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your all missing the point the fan only works when when ac is switch on[high speed only] the fan never kicks in unless ac is switch on

Last edited by rusty metal; 10th October 2018 at 07:44..
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Old 10th October 2018, 07:54   #7
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Usually on a two speed fan if the resistor fails then it will pulse on and off on highspeed with AC on. This is unless the condenser is in poor condition where the fan may stay on high speed masking the fact the resistor has failed.

For the cooling system it is my understanding that the same relays are used in the junction box to bring on the slow and high speeds. again if the resistor has failed then the fan wouldn't come on until the higher temp is reached

Have you checked the actual temp of the engine using the diagnostics in the instrument cluster?

It is possible/probable that you have a number of issues that individually wouldn't cause an issue but together do.
Stuck thermostat
Failed slow speed relay
Failed slow speed resistor
inefficient condenser

I also stand to be corrected on this by guru's such as Russ but I suppose there could be a fault with the ECU not sending the signal to the relay to say the engine is too hot.??
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Old 10th October 2018, 08:04   #8
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the car starts to over heat and the fan dont come in till i turn the ac on then cools down instantly
I think this is the point we need to clarify
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Old 10th October 2018, 08:41   #9
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Yes I agree Dave. There are plenty of these diesel cars running with faulty fans with no problem at all if the air con is left switched off.

In normal operation the engine coolant temperature never gets high enough to trigger the low speed, so although there maybe a fault with the fan, if the engine is overheating, and assuming you aren't towing something heavy, then there is another fault with the engine cooling system.
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Old 10th October 2018, 10:03   #10
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Quote:
Originally Posted by rusty metal View Post
no its not correct i know the way is should be i've owned it since it was 3 years old [13 years] the car starts to over heat and the fan dont come in till i turn the ac on then cools down instanly

Might just be worth making sure that everyone is on the same page re: what is meant by 'over heat'.



Does the temp gauge needle rise above the 9 O'clock (horizontal) position? If so: by how much? Or, are you reading the temperature from the Instrument Pack diagnostic display, if so - what temperature is it reaching before you turn on the AC?


From the way you write '...till I turn the ac on then cools down instantly' (my typo corrections). It sounds to me like you may even mean that the air through the cabin vents is uncomfortably hot - and when you turn on the the AC on it cools down.


I think also that we are all visualising that you have the full climate control type of AC with the digital display - not the manual 3 knobs and an AC on/off button?
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