Hi, noticed than my fan seems to stay on constantly. Replaced coolant sensor but still no change. I have to disconnect wire from fan to stop battery draining obviously not ideal. Can it be anything else? Please help.

have you unplugged the sensor?

what engine and has it got air con?

is it running whilst the ignition is off ?

That happen to my mates car, ran out of water and fan went on for ages after the engine stopped. Blew engine or something in the end.

Yeh replaced it with a second hand one and when I connected the fan it came on

Yes

Does it come on when the engine is stone cold?

pull the cover in front of the battery, three small relays in a row, think the middle one is for the fan, pull it and check it. check for corrosion/bad connections as well. two small clips to the rear and it lifts out so you can check connections underneath.

you used a second hand temp sensor?

I have unplugged it so its not on now. But when I go to use it I then re-connect and it comes on straight away.

I`d get a new sensor.

or a new car, bloody clios

Plus, make sure the wiring connectors are the right way round. One car had 3 different types of sensors listed, 2 with 3 pins and one with 2 pins. Turned out to be the 3rd to be tried, one with 3 pins, yet only 2 wires on the connector. Stupid designers/mechanics/fools..

Might have to do that.

That's not I want to hear

I've experienced this problem in the past, but on Peugeots.

The problem was dirt and grime on the radiator fan relay. Its positioned at the front of the car and rather exposed. I reckon there was current getting through to activate the relay, but not the contact which de-activated the fan.

A clean and re-protection of the contacts sorted it.

It might not be the case for you but well worth a try. There are plenty of guides on the net showing how to test a relay.