I hope we find the same solution to a slightly different problem.  Staying
tuned.

My Haynes manual suggests it can be seen once the blower motor is
removed

i) For safety, remove the negative terminal on the battery. (note that a
bit further down I suggest testing by shorting across the fuse - the
power needs to be one for this)

 This will remove the power from the radio which will then need the
security code to make it works again. Removing the power will also reset
your engine management system. The car may then appear to be a bit
'lumpy' for a few miles while the engine management re-learns the
optimum setting(s).

ii) Remove the 3 screws securing the lower passenger side foot-well trim
and withdraw the panel.

iii) Remove the 3 screws from the glove box hinge and remove the glove
box.  Firmly press both sides of the glove- box to distort the plastic
to enable removal.

iv) Undo the securing screw and detach the ventilation hose from the
blower motor.

v) Unplug the motor's electrical connector and undo the three screws
holding the motor in place. Remove motor.

vi) The motor control resistor can be can be removed by undoing the
screw at one end of the assembly - pull the resistor out of the housing.

I have successfully performed thermal fuse surgery on two similar
assemblies - although not on my focus.

Below is something I posted a year or two back with new edits

The speed of the fan in the first three positions is controlled by a
bank of resistors which are relatively large and get hot. The thermal
fuse is in series with these resistors and physically almost touching
them.  When the fuse blows the first three position don't work.  In the
final switch position the battery voltage goes straight across the
motor, bypassing resistors and thermal fuse network, hence it works.

The resistor and fuse assembly is usually mounted in the blower motor
air stream and I believe that you can get to the resistor assembly by
removing the blower motor in the Focus. Release the glove box by flexing
the plastic sides (a _tiny_ bit of force may be required). The glove box
then hangs out of the way and you can see the blower motor and fixings.

The fuse is a two legged device which when it reaches a preset
temperature blows permanently open circuit.

I would assume that the way the module is constructed that the fuse
alone isn't a replaceable part and that a dealer would charge for the
whole module. However it is a do-it-yourself fix if you can find the
motor 'resistor module' and have some basic electrical soldering
capabilities.

In the UK the a replacement thermal fuse (for the do-it-yourself repair)
can be obtained quite cheaply (0.5 GPB or less than $1 US) from
electronic component stores.

<http://www.maplin.co.uk/>

or

<http://rswww.com>

When buying the replacement fuses the one you want is probably towards
the higher end of the temperature range (150+ degrees C).

Before replacing the thermal fuse check it with a meter to see if it
open circuit or temporality short across it to see if the motor works on
the lower  speed settings.

Despite the warnings about not to solder to the leads of a thermal fuse
I've successfully used a high wattage soldering gun and _quickly_
soldered at the ends of the leads. Obviously as it is a one time thermal
fuse leaving the soldering iron in contact too long will heat up the
whole device to a temperature where the fuse blows. As they are cheap it
may be worth ordering a couple  - just in case :) You could attach a
crocodile clip or bulldog clip as a heat-sink to the body of the fuse
while soldering to reduce the heat build-up.

Cut out the old thermal fuse but leave about quarter of an inch of the
lead on each side that is crimped to the terminals on the assembly.
Leaving a bit of the old lead in place will make soldering the new
component easier. Soldering to the terminal post is difficult unless you
can clean it up with a small file.

(It doesn't matter which way around the fuse is fitted -it isn't
polarised.)

The problem may have been caused as a result of water getting into the
system and the blower motor not running as smoothly as it should. On
previous cars where I have fixed identical problems the motor shafts
were rusty and some lubrication (ONE DROP of engine oil from the
dip-stick) was applied to the motor shaft bearing area.

Before attempting this repair check out the newsgroup archives at

<http://groups.google.com>

Type 'thermal fuse blower motor' into the search box (without the
quotation marks).

The advice given for other cars is valid.

This is not an Internet forum, it is a newsgroup.

There is no UK Focus newsgroup.

By casual observation, European posts here outnumber US ones by about 3 to
1.

HTH

Chris