As soon as the ignition is turned on the heater/cooler fan for the internal airconditioning comes on & stays on. The heater controls seem to have no effect & have checked the pcb selector switch/resitor network and all seems ok (in the control module). The slider has an Auto. Off & slider for increasing motor speed. Even in the off position the fan still runs at full speed - suspect short somewhere but cannot locate. Any ideas welcome.

Ray Chatfield, March 2008

I have just cured this problem on my 2001 with air con. Turned out to be the diode control unit built into the motor......Remove lower panel under dash on passengers side,this will expose the heater unit. Disconnect plug & single loose wire from blower motor, remove three screws & remove blower motor unit from housing. The diode pack can now be seen..... Disconnect the two wires from the diode pack to the motor & the plug into the side of it. Now remove the motor & fan from its casing, ( some are just rubber mounted push fit, some have single screw in end )
You can now remove diode pack held in by two screws.
These are available from Citroen but at a price. I managed to find a good secondhand one. You may be able to find a good complete blower motor, if so job should only take 15 minutes. Re-assemble is the reverse of dismantling.

Ken, July 2008

i have this fault on a ctroen picasso and a new ignition switch cured the fault.

mick, June 2008