The Electrics, Dashboard and Heater 12 Heater (1)
24 Citroen XM Internet Reference Version 1.0
3/3/99
12 Heater (1)
Blower always on
After some mothst without technical problems on my XM, it’s now time for a new technical challenge:
My blower for the heating system keeps blowing, even if it is switched off (position 0) This happended
sometimes before, and cured itself magically. But now it is a non-stop hurricane in my car. I think it’s
acontact problem because sometimes it is windless for a few seconds. Swithing on and off the climate
control does not help. Also banging on various places (near the switch and on the blower just above the
feet of the passenger) did not help. I cleaned the contacts round the blower without succes.
Dismantling the heater panel
Does anyone know how to open a part of the dasboard near the blower control.
As an answer I’m quoting from the Citroënian (october 1997 issue):
..... To gain access pull off the three rotatable controls in turn (be careful not to lose the metal tabs which
give the controls a tight fit on the shaft), pull the sliding control off its shaft. The two screws that hold this
small piece of facia can now be removed, followed by the panel.
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Heater control failure
Does anyone know what could cause the heater control to fail?
ie No climatic control, no speed control - only off or full on when the control is moved to full.
I’ve checked the connections between the motor control module, the central dashboard control and the
sensor in the roof and all is ok.
The sensor in the roof works - multimeter connected across connector in dashboard showed the
resistance to change when I put my finger on the thermistor. What should the resistance be?
I also found a dashboard control in a scrapyard, but that didn’t make any difference.
I’ve also changed the power transistors on the motor module - no difference apart from slower motor
speed! I now suspect the ’potted’ surface mounted components. Does anybody know what waveforms/
voltage levels should be found around the circuit?
If it is the motor module, then does anybody know where to get one at a sensible (i.e. a lot less than 70
UK pounds!) price in the UK or mail-order from overseas?
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I’ve just got my heater working again by replacing the blower motor. I could have just replaced the
control board within the motor, but Citroen wanted £85 for a circuit board with a few surface mount
components and two power transistors. I eventually found a secondhand motor in a scrapyard - but they
even wanted £50 for that! It seems that scrapyards buy XM for very little, but then charge prices that
reflect the new high prices.
Heater Computer
Did you know the heater system on an XM has its own computer (situated next to the hydractive and
injection computer [ and ABS]).
Have you reset this computer?
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