Ive got a 51 plate Focus 1.6, the heater fan will only work on position 4. Ive had the switch out and its fine, ive also 'shorted out' the terminals on the switch plug for each corresponding switch position and again the fan only runs on position 4, has anyone any idea what the problem might be......
Thanks and Happy New Year

iirc Think there's a Known problem with the Heater Motor on these
and you get the same symptoms you describe

[Edited on 31/12/10 by perksy]

Fill be the resistor for the heater burnt out, iirc they are only about £12 from ford

Resistor pack would be my first thought.

Yup Mondeos do the same thing.

I would deffo say it's the resistor pack hope it's not like remained were it burns the wiring as well

Yep will deffo be the resistor pack. there are different wound coils for each fan speed. position 4 is full speed which either has a much bigger winding, or powers directly through.

On the Vauxhall they have a thermal fuse which is normally what has blown. you can buy replacements from Maplins for a few pence, and is very easy to repair on the vauxhall. Cant see it being much of a different design on other cars

If the resistors are blown I think that it's worth checking that the fan spins freely (if you can get to it?).

I had a Vauxhall Astra Mk1 and when it got old the resistors in the Heater Fan circuit started to smell. The problem was that the fan motor had started to seize up. After taking the motor apart and cleaning the bearings the motor span OK and the resistors didn't smell any more.
Having worked in power electronics my nose was attuned to the smell of overheating wire wound resistors so I picked it up early but if left they would surely have burnt out.
The fan lived in a fairly hostile environment pulling the air and dust through so no surprise that after about 8 years they were gummed up.

ok thanks to all