Strange, but as per the title, our fan dial now only works on full blast. My expectation would be that it wouldn't work at all, but there we go.

So, what are your thoughts as to what to do about this? Replace the switch itself? As it happens it seems to want to come out quite easily (it glows green inside, like something out of Star Trek!)

TIA

Duff heater resistor pack, quite a common fault-

http://www.ebay.co.uk/itm/New-Ford-Focus-Fiesta-Mondeo-KA-Heater-Resistor-Motor-Fan-Blower-1311115-/391074465248?hash=item5b0ddac5e0:g:6tUAAOSwBahVJRCC

It's the heater resistor pack that needs replacing, it's quite common for these to fail.

The genuine one: http://www.fordpartsuk.com/shop/ford_focus_heater_resistor_f_1311115_c_104.htm or you can get aftermarket ones on ebay for about £12

You'll need to remove the glovebox, to make it easier to get to the resistor pack. Which is held in place with 8mm bolt. It's a simple job of of removing the failed one and plugging in the new one.

While you're about it, it is a wise move to replace the pollen filter

It appears £7.50 is the current aftermarket price on ebay: not £12

http://www.ebay.co.uk/itm/FOCUS-HEATER-RESISTOR-1998-2005-BRAND-NEW/281419995873?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140107083358%26meid%3D5338aa8717484e1585a2615418175e0c%26pid%3D100011%26rk%3D1%26rkt%3D10%26sd%3D271371674168

Thanks guys.

Now, you say it's the HEATER Resistor Pack, but there does still seem to be heat generated judging by what I feel drifting out of the dashboard vents, it's only the fan that's not working to push (pull?) that heat out in to the interior of the car, except when I put it to setting four.

Does any of that matter? I'm guessing not, as three of you seem to agree, and I admit I know basically jack-all about cars. I just want to be sure.

:)

It's not a heater resistor, technically it's the blower motor resistor. It doesn't have any affect of the temperature of the air, it's only job is to reduce the fan speed.

Replacement ordered, along with the pollen filter.

And it all looks remarkably easy to replace:

https://www.youtube.com/watch?v=sRi3UdWb0ho

As does replacing the pollen filter as suggested by GMX (although I was expecting the work for this to be in the same area as the resistor...what made you suggest it, GMX?)

https://www.youtube.com/watch?v=qpFj-lCWZgY

Anyhoo, thanks for your speedy responses, folks.

Next project: Replace boot door gas struts.

I have had 3 resisters fitted now and all have blown, if thats the right word.

Someone said I need an auto electrician now.

Any thoughts on that please?

You probably need a new fan motor.

in my wife's focus mk1 it failed twice. I then inspected the fan motor, it was stiff. I lubricated the bearings (carefully as you don't want oil on the commutator). All was fine after that.   the resistor pack has a thermal fuse on it. Both time it was just the thermal fuse, so rather than but a new resistor pack I soldered a new thermal fuse on to the existing resistor pack.  Carefully though as you don't want the thermal fuse to blow from too much heat.   A thermal fuse blows when it reaches a certain heat as opposed to certain amps load.  Widely used in hair straighteners etc. 

i think the stiffness caused extra electrical load which meant the resistors got hotter then they should which blew the thermal fuse (just as it should do before the hot resistors cause a fire). Additionally the resistor pack is cooled by the airflow through the ducting so if the fan is stiff and runs slower then the airflow is lower and won't cool the resistor as well as it should

and more: ours was 2001 mk1 , your 2003 will be the mk1.5 facelift but i would imagine the fan arrangement would be the same. quite easy to get to behind glovebox.  On some other cars you have to do tons of dismantling to get to heater fan but ford made it easy on mk1 focus