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mrpj

Cooling Fan.

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I could be totally wrong and imagining it, but I'm sure that the radiator/condensor fan ran continuously when the a/c was operating. Since a recent service (coincidence?) I have noticed that the fan starts and stops with the loading and unloading of the a/c compressor.

Would someone either do me a big favour and check what happens with their Mk3 Yaris when the a/c is on? Or alternatively confirm which is the correct operation.

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Can't confirm on a Yaris, but this is correct operation (kicking in and out the fan) for Fiat's. I wouldn't deem it unusual myself, it'll only run when required to limit impact on fuel economy.

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On both of my mk 2s, the cooling fan runs with the a/c on when I've been stationery for a while, especially on warm or humid days. Noticed in the learner car that it's fired up as soon as I've activated the a/c. It'll just be to keep the system blowing cold. I first wondered about it until the other car did that too. Great to hear the cooling fan as I otherwise never hear it come on unless I'm in bad traffic.

Hope this helps

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Thanks both.

Adam - does the fan come on and stay on though? My fan does come on with the a/c but stops and starts in sync. with the compressor loading and unloading. So starts and maybe four or five seconds, stops. This is with the car stopped of course.

I realise, at the moment temperatures aren't that high so the a/c doesn't have to work too much.

Prior to the service and when I stopped the engine I could hear the cooling fan running down quite clearly. I know the fan wasn't running due to cooling water temp. rising. Now when I stop the engine I don't hear the cooling fan running down anymore.

Continuous stopping and starting every three/four seconds can't be good for either the fan motor or it's relay. It complicates things with the fan having two functions, to cool the radiator if required and cool the a/c condensor.

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Continuous stopping and starting every three/four seconds can't be good for either the fan motor or it's relay.

Motors and relays are designed to constantly start and stop, so doing so shouldn't do it any harm.

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Continuous stopping and starting every three/four seconds can't be good for either the fan motor or it's relay.

Motors and relays are designed to constantly start and stop, so doing so shouldn't do it any harm.

Really? I'd like to compare the longevity between a motor and switch(relay) that is started and stopped every 3 or four seconds to similar when run continuously. I suspect the former will go belly up long before the latter. On/off operation can't be much good for the motor/fan mountings/bearings either with the starting torque being applied every three or four seconds.

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We're not talking overly high torque levels though, its a radiator cooling fan, not a large heavy industrial cooling tower fan - it all needs to be put into perspective. The running cost of it cycling rather than being constant and reducing fuel consumption will be far less than any potential wear and replacement costs as a result - the fan motor will normally outlast a car, and the relay will be a few £ at most normally if that fails due to mechanical wear.

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If fan wear due to stop/start of the electric motor was a problem it would have become apparent when airconditioning became common in cars,

Ie. the early 1960s. !!

It's a straw man theory .

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