Air conditioning fan relay switch
 

For the last few weeks, there has been an occasional whining noise from under the bonnet when the air conditioning was switched on. It sounded to me as though a bearing was faulty.

The car has been examined by a local garage specialising in air conditioning, however, and they tell me that the problem lies with the relay which is supposed to switch the fan on when needed. Apparently, the relay has failed and so the fan does not come on when it should. (The fan itself is not at fault, as it does come on when triggered by the separate relay linked to the engine cooling system.)

The mechanic tells me that a new relay costs £315, and adding two hours' labour brings the cost of replacing it to £521. Much as I love the car, I cannot justify spending this amount on a car which is almost 10 years old (especially as I have just paid £325 to replace the water pump, on top of over £700 for a new clutch last year). For now, I have simply switched the climate control onto "Economy" and open windows as necessary.

My question is, does anyone know where these relays can be bought and fitted more cheaply, please?

Sounds suspiciously like the slow speed has failed on the fan to me :(

Use the on board diagnostics to see at what engine temp the fan activates. If it doesn't come on at 100deg or there abouts, the slow speed has failed and that usually will also have taken the medium speed with it.

It is quite possible you only have the high speed working that is stopping the car from overheating.

Your 'mechanic' is taking you for a ride. He obviously knows that you know nothing, so he's simply rubbing his hands at the prospects.

Say 'no thanks' and come back to the forum for a realistic diagnosis. It will probably be fairly simple and nowhere near £500 to fix.

TC

Charles, are you free to go to Doncaster next Weekend? If so there is a yorkshire workshop meet spread over 2 days, any work done there is free. I will be there among others who know a few bits and bats about the cars ;) :D. Let us know if you are coming :)

:iagree:
Charles,

I'd just like to add my support to what's been said. Please don't use that garage again. They don't appear to know how the 75/ZT air conditioning & cooling system works and rather than finding out they are telling you a load of rubbish.

As Stocktake says, monitor the actual coolant temperature to check that the engine fan triggers at 100 degrees C. Alternatively, start the engine from cold, press the 'demist' button and check that the engine cooling fan is running.

Other possible causes of a whining noise when air con. is operated are a slack or damaged auxiliary drive belt, an inefficient condenser or other fault with the air conditioning. But the first thing to check is the engine fan.

Simon.

Thanks for the replies. I forgot to mention in my original post that I have run the climate control diagnosis checks and the result was "no fault". I can also confirm that there is an audible sound when the air conditioning comes on, so the clutch is "kicking in".

I suspect that there is a problem with either the fan or the relay which triggers it. Obviously I can't see the fan, but what worries me is that I can't hear it either, although I can't say for certain that it isn't coming on because of the noise of the engine. I have tried switching the demister on with the engine off and I can hear the fan then, so it can't be totally dead. Does this help?

I might be able to make the Doncaster meet and that would seem to be the best way forward. It depends whether I can get out of another commitment. Dave, can you give me some idea of when you will be there? Would Sunday afternoon be any good, or is that too late?

The climate control diagnostics applies only to the temperature and distribution system inside the car. It does not diagnose faults with the equipment under the bonnet including the radiator fan.

Charles,

The way of telling whether your fan is working is as follows:

1. Start the engine from cold.
2. Press the 'demist' button on the air con. control panel.
3. Get out of the car and, with the bonnet closed, look through the radiator grille.
4. Can you see and hear the radiator fan running?

Simon.

Have now tried this: the fan doesn't seem to move at all.

Hi Charles
As above Dave (Stocktake):bowdown: knows and thing or two about these fans ;) he and i managed to fit one from scratch bumper off etc at the last nano i think in 50mins if i remember right if you can not make the doncaster meet try getting to the wolverhampton weekend nano 21st and 22nd Arctic.

Thanks, Arctic. I've exchanged PM's with Stocktake and am hoping to see him at the Doncaster meet.

Charles.