406 Coupe fan constantly on.

[bigozz]

I've been nurse maiding a 97 3.0 Coupe for about 8 years now, and she's really starting to show her age.

The most recent problem is the cooling fan. When the ignition is turned on, the fan goes into overdrive ofter about 5 seconds.

Is it likely to be a relay or a sensor? And how do I check?

Thanks in advance.

[mjb]

Presuming you mean the radiator fans as opposed to the interior blower, I'd say it's a duff coolant temperature sensor (about £15) or just a broken connector to it. It's *somewhere* on the right hand side of the engine (the end closest to the battery) near the top, but I haven't actually looked for mine yet so I can't be any clearer sorry

[steve_earwig]

I seem to remember someone saying the fans will constantly run full tilt if you disonnnect the sensor... hold on...

You can test if the fans are working by pulling the plug from the coolant temperature sensor at the back of the thermostat housing. That should cause the fans to run at full speed when the ignition's on

Aha! It was that clever mjb bloke again

[mjb]

Aha! It was that clever mjb bloke again

[bigozz]

Thanks for the responses!

When the ignition is on both fans start a sequence of 'low, then high, then off' and repeats.

Is this likely to be the coolant temperature sensor that you've mentioned mjb?

Cheers guys.