Bizarre fault cooling fan Xantia Activa won't turn off. Help!

[petef]

My 1996 series 1 Activa has been performing well in France this week. However right at the end of it's last journey before I return to the UK in a different car it has a dicky fit. Basically the left hand engine cooling fan will not turn off. Even removing the appropriate fuse - 30amp fuse 3 under the bonnet has no effect - it keeps on running. The only way to stop it is to disconnect the battery. I am completely flummoxed. The car has air conditioning which was on at the time the fan refused to turn off, if this is relevant. Anybody any ideas....?

[white exec]

The two fans should always operate simultaneously, and at the same speed (Low or High).

The fault you describe sounds like one of the three relays which operate the fans (switching them on, and from series (slow-speed) to parallel (high-speed) is misbehaving . . . either stuck closed, or maybe disconnected.

Try checking the relays out (dirty contacts internally, or on the bases). Sometimes, just unplugging and replugging them a few times can cure a poor contact.

If stuck, post your VIN, and we can dig out the exact circuit diagram. There were minor differences in fan operation on Xantia.

[petef]

Thanks Chris.
I don't remember the right hand fan ever working - must check it out. After looking in the Haynes Manual I finally found what must be a similar 2 fan set up for a turbo D. This pointed me in the direction of the fan relays being served directly by maxi fuses. Sure enough removing maxi fuse F stopped the fan. I suspect you are right, the relay for the left hand fan has welded itself on all the time. Hopefully I can get to it by just removing the grill? When I replaced the fan a long while back I'm sure the bumper had to come off too. In the meantime I would appreciate the relevant wiring diagram for my car Vin VF7**************[VIN obfuscated, can be read by forum staff] so I can be more certain of what is going on.Thanks again

Peter

[Clogzz]

Had that; the relay stuck shut and I pulled a maxi fuse out to stop it.
I kept driving like that for weeks because it was winter and the fans never went to high speed.
I got to the relay box by removing the grill, certainly did not take the bumper off.
Somehow the relay had come good by then but I swapped it for the change-over relay where it won’t cause much trouble.

[white exec]

That is essentially the right circuit diagram for the 3-relay system, with helpful annotation for the two speeds.

For your car (1995 Activa, with A/C, RP6888=18Sep1995 - so Series 1) this is the circuit in Citroen's Electrical Wiring manual:
↓ click to enlarge

If replacing the relays, they are all standard 30/40A 12v automotive type.
The changeover one is 5-pin, and must be in the right socket for the system to work.
Although the other two are only "make" 4-pin type, you can play safe by using 5-pin changeover ones in all three sockets.

If the sockets are "up front" near the nose-cone, they can suffer from weathering and socket/pin corrosion.

Check/replace the relays and their sockets first.
The non-working fan could be
- its (maxi) fuse blown or poor fuse contact
- fan gone open circuit - in which case Slow speed would not work at all, only Fast with one good fan operating
- fan gone short circuit or seized - Slow speed would show up as Fast, and Fast speed (fans in parallel) would cause a blown fuse

Hope helpful.
Let us know how you get on.

[petef]

Thanks for all the information. I've had to leave the car in France and, for the moment, I can't investigate further. When I get back to it, I will try replacing the left hand fan relay as a starting point and see if that cures the problem. I will also check out all the suggested things to look at with the right hand fan and report back in due course.
Thanks again