CITROEN XM Internet Reference page 29

13 Heater (2) The Electrics, Dashboard and Heater
Heater fan fault finding and solution
Heater fan on a 1990 XM 2.0Si.
The problem was that following a prolonged period of running on fan position three, the fan continued to
run at that speed irrespective of switch selection. My "Electrical Friend" checked out the switch and as
far as possible the relevant relays (which were slightly different to those shown in the Revue Technique
diagrams).
I phoned Andy Bumett who said the problem was in the Diode Pack bolted to the motor and the best
solution was to obtain a complete replacement motor from a scrapyard. No luck with the local
scrapyards (not many XMs round here, even fewer broken ones) and the Citroen dealer quoted £185 for
a complete motor or £84 for just the electronics plus VAT of course. So back to the "Electrical Friend".
The motor was easily removed, having first removed the panel under the glove box on the passenger's
side. This exposes the fuse box and to be on the safe side fuse F25 was removed. Three screws and a
couple of electrical connectors release the motor.
Sure enough there is an electronic pack, held by two screws, on the motor. Removing the screws and
carefully easing the fan away from the motor body gave sufficient clearance to free the electronic pack.
(Do not try to remove the fan from the motor shaft). Investigation showed that among many components
there are two transistors, one was found to be open circuit and the other to have a short circuit
The numbers on the transistors (FW25025A) were not recognised but two MJ15004, 140V, 20A, 200W
P.N.P . transistors were obtained, fitted and the system re-assembled and checked. I think the fan runs
slightly slower now but it is working properly. l must say that without the "electrical Friend" I would have
widened the search for a scrap unit before swallowing hard and paying the Citroen price.
(Thanks to John Davidson and David Evans)
Replacing heater controls.
They are a push fit onto a shaft, being kept tight by a piece of spring steel. With age and removal/
refitting for fascia bulb renewals, the plastic breaks from the tension of the spring steel. All mine broke,
to the extent that I had to use just one to operate all three. l replaced them at a ridiculous cost of £24.55
for the kit of three, pity I hadn't the time to look around a few scrapyards. That's it, keep up the good
work. Cheers. (Thanks to Kevin B Spruce and the CCC)
Cooling systems
I have been given a huge incentive to change my car's coolant by a letter from Dave Weber, He writes
Sorry to hear of H603 GDP's leaking heater. l have had heater problems too, on a massive scale and my
experience may be helpful.
In fact, the only problems I have had with my 1990 2.0 Si in the 40,000 miles I have covered since
getting the car, a year and a-half ago, have been related to the cooling system.
First to go was a core plug. Then the lower radiator hose sprang a leak. And, a few months later, I too
noticed a very wet floor in the driver's compartment, traceable to the heater matrix. l had never ever had
a heater matrix fail on a car. A local branch of Serck Marston supplied a new matrix, the same Valeo unit
as Citroen uses, and I thought my troubles were over.
Not a bit. Three months later, the new matrix began leaking. The little bending end pipes had broken at
the seams, as if it was a defective unit. Serck Marston thought so, too, and replaced it free.
I did think about this time that I might be building up too much pressure in the cooling system caused by
either a cracked head or a broken head gasket that was jamming cylinder compression into the system,
but we ran a chemical check of the coolant and there was no trace of carbon monoxide.
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