CDTI rad fan not switching off

[french dave]

Hello
The rad fan on my fathers 2004 CDTI 110k miles has a problem.
Today after a 5 mile drive, he turned off the engine and the fan stuck on

He got to his local garage who disconnected the battery and reconnected it to stop it.
Then drove 4 miles home, and it stayed on. For more than 30 minutes
He has AA home start so called them, who did the same and said rad fan control unit was at fault
However i think that the problem could be a stuck relay.
Am I right
My father will have to get the work done, as he is 82, and I live in France whilst he is in southampton.
Any thoughts please

[T-Cut]

Originally Posted by french dave

However i think that the problem could be a stuck relay.
Am I right

Possibly. The fan motor has a permanent live supply, with on/off and speed control operating through the earth circuitry. A stuck relay will cause it so worth swapping them for new ones. There are other running-on issues common to diesels that concern the printed circuit board. You might also check the power connectorinthe wheel arch for water ingress.

TC

[french dave]

Originally Posted by T-Cut

Possibly. The fan motor has a permanent live supply, with on/off and speed control operating through the earth circuitry. A stuck relay will cause it so worth swapping them for new ones. There are other running-on issues common to diesels that concern the printed circuit board. You might also check the power connectorinthe wheel arch for water ingress.

TC

I assume we are talking about the relays behind the front bumper. Is there 3 , two used and a spare?

[T-Cut]

Originally Posted by french dave

I assume we are talking about the relays behind the front bumper.

That's correct. They're in the control box mounted on the fan framework.

Is there 3 , two used and a spare?

I believe the number varies depending on the motor version (3-speed or 2-speed). There isn't a spare. Whatever, they're off the Halford's shelf type relays.

TC

[SD1too]

Originally Posted by french dave

However i think that the problem could be a stuck relay. Am I right

I'd say you're hopeful Dave. Relays are incredibly reliable. It's far, far more likely to be a faulty PCB. If so, talk to FrenchMike who can repair it for you.

Simon

[french dave]

Originally Posted by SD1too

I'd say you're hopeful Dave. Relays are incredibly reliable. It's far, far more likely to be a faulty PCB. If so, talk to FrenchMike who can repair it for you.

Simon

Trouble is the car is in Southampton.

[Arctic]

HI Dave.
Try and get your dad to drive to Chris (cb750chris ) Portsmouth maybe an hour from Southampton ? he should be able to help, drop him a PM

https://www.the75andztclub.co.uk/for...=newpm&u=14945

[COLVERT]

What would it be if disconnecting the battery would switch it off ???

A stuck relay would stay stuck wouldn't it ??

A burned PCB would remain burned. --

Odd problem.

[french dave]

Originally Posted by COLVERT

What would it be if disconnecting the battery would switch it off ???

A stuck relay would stay stuck wouldn't it ??

A burned PCB would remain burned. --

Odd problem.

Yes but it started again when the battery was reconnected

[cb750chris]

PM sent, we can look at this whenever your dad is available.

First question though - he didn't have the aircon on, did he? As that will put the fan on until the ignition turns off (apologies if that is a bit too obvious)

Also, does he have an inline stat fitted, as I have known one of these to fail closed, so the fan could be doing what it should (although 30 mins is a bit long, I would have expected the engine to have cooled down sufficient in that time)

Chris