Heater Problems Flat Battery

[nplatts]

We have a 2005 XC90 with a very strange problem, the heater controls are unresponsive you can turn the heater speed control and nothing happens the lights turn on but the heater does not, you can turn on the auto setting but if you put the temp to the top the fan just stays running slowley. the only control that seems to work is the front screen demist. The most annoying issue is when you turn off the ignition - remove the key and lock the car you can hear the heater fan continuing to run , if you dont remove the fuse(the climate control fuse) the car battery will be flat in the morning ! we have been removing the fuse now every evening for a few weeks and it's a real pain.

I have read somwhere that another canbus item (the drivers electric seat) could be creating errors on the network causing the system to be unresponsive ? has anybody any more information ?

Just as a foot not the windscreen washer has packed up as well ???

[Art]

I wonder if your problem could be related to a defective blower fan potentiometer assuming that this is a recurring event and not intermittent.

As far as the windshield washer function goes, first check the fuse for the washer pump in the engine compartment.

[nplatts]

Could be, thinking on when the fault first started messing around with the heater speed control would sometimes rectify the problem and the Climate would wok correectly for the duration of the jorney. but now nothing happens when you turn it.