12 Heater (1) The Electrics, Dashboard and Heater
Citroen XM Internet Reference Version 1.0 25
3/3/99
If you don’t know how to do that, try disconnect the battery for about 10 minutes. This should reset the
computers.
If this does not work you should use an ELIT to read fault diagnosis in the heater computer.
Servo Motor
Does anyone know how to fix a heater that is continually hot, even although the heater control is
switched off.
The car is a 1990 XM SEi 2.0 Auto
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With mine (1992 2.0i) it was the servo motor that drives an air distribution flap to adjust temperature in
response to the temperature sensor in the overhead light fitting and the temperature control on the
dashboard. But your system may be quite different.
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On my SED it was always cold. I replaced the servo motor which I found on the left side of the heater
and this did the trick. If you take out the glove box you will see the black device held by 2 screws. It
should move when you turn the temperature dial. In the mean time you can attach a wire to the arm the
motor moves and control it manually!
Sometimes Breakers will let you try the device you suspect before purchase.
Blower always stuck on full
My XM’s blower stuck on full, then stuck on off unless switched to full.
The cure was to replace the control board on the motor. I actually replaced the whole motor because a
secondhand motor was 30 UK pounds cheaper than a new control board.
There is another control board (with micro processor!) behind the three control switches. Remove these
switches to get to it. A simple way of removing the switches is to feed a length of tinned copper wire in
behind the switch, join the two end together by twisting, then put a screwdriver through the loop and give
the wire a sharp tug. The wire will probably snap, but the switch comes off without damaging it or the
surrounding plastic.
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Hi, I had this problem and it turned out to be the metal flat spring inside the blower control knob. Grip the
knob with a suitable tool[pliers wrapped in a cloth] and pull it off. look to see if the spring is present or if
the plastic that holds it in place is not broken. Mine was broken and I repaired it with araldite. also the
knob only goes on one way for it to correctly turn the blower motor settings.
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On the heater front. I found that removing the heater control knobs and then the panel behind them
allows easy access to any bulbs which may be burnt out. I put a rubber washing up glove on and found
that this gave just enough friction between my fingers and the controls to pull them away cleanly without
damaging them. (Let’s see, that’s wire, pliers and gloves, any more suggestions?)
A result!
Thank you all for pointing me in the right direction with regard to myheater problem.
Removal of 4 screws and off came the glove box lid to reveal plastic ducting and coloured wiring looms.
A quick look in the bottom right hand corner and there was the little servo motor but how to unscrew it.
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