Ford Focus: internal blower/fan dont work

In message <co.uk>, Billy Who?
<com> wrote

 

Has it completely failed or does it still work on the fastest setting?
--
Alan
mailto:clara.co.uk

In message <co.uk>, Billy Who?
<com> wrote 


UK Focus circuit at:
<http://www.amacleod.clara.co.uk/focus/>

If the blower doesn't work at any setting
i) Check the fuse
ii) It is not unknown for the switch to mechanically fail

Fuse for the blower motor is in the fuse box in the engine compartment.

If the blower works at the fastest setting but not the lower three
setting then the most likely cause is a blown thermal fuse. If you have
some experience with a soldering iron there is a cheap Do it Yourself
fix for this problem.

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In a UK Focus to remove the blower motor switch:

Disconnect the battery (for safety reasons)

Remove the radio/cassette. If you disconnect the battery or radio make
sure that you have the 4 digit security code (and instructions) that you
need to enter to make the radio work again.
See
<http://www.myfordfocus.com/how-to/headunit-removal.htm>

Undo the four securing screws from inside the radio/cassette player
aperture, then carefully unclip the heater control panel from its three
retaining clips in the fascia.

Disconnect the wiring connector from the switches as the control panel
is being removed.

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To get at the blower motor or to fix the thermal fuse: (re-post of a
previous reply in this newsgroup)

Note: The thermal fuse is different to those fitted in the fuse boxes.

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>

I've included the references to the devices plus a circuit of the blower
motor circuit on

< http://www.amacleod.clara.co.uk/focus/index.htm>

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.

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.
--
Alan
mailto:clara.co.uk