Planning the next
AO Silver Member
Join Date: May 2007
Location: United Kingdom
Could be temperature related.
What I'd probably do -
Have a piece of thickish wire to hand and next time it it plays up -
Get under the passenger side footwell ( ignition on ) and touch one end of your test wire to the speed controller side of the fan ( Blue/Black wire - NOT the orange one! ) and the other end to a suitable bit of car body*. If the fan starts up, that's good and shows the fan is OK.
At the speed controller, touch the Blue/Black wire again earth. If the fan starts up ( again full speed ) the wiring between the fan and speed controller is good.
Still at the speed controller touch the other 3 wires to earth one at a time ( white, grey and green with aircon , white/green, grey/red, green with no aircon ) - the fan should go at the three lower speeds. If all that is OK, the speed controller can be ruled out.
If all that works OK, it points to the switch being the culprit or the wiring on either side of the switch.
One final test if you have aircon. Turn the speed switch to 0 and the fan should run at a low speed when the aircon is on ( this functionality uses different wiring within the switch ). Also try pressing in the recirculation button as that has an effect too.
* I'd suggest removing the carpeted side trim and cleaning a bit of paint off the bracket that supports the dashboard under the radio.