Electrical problem help !

My five position switch for the fan (heat, a/c) only works on the high setting. It still clicks at 0 through 3, but only comes on when on 4. I would guess it isn't a fuze as it wouldn't work at all if that what what was
wrong. Anybody have any ideas. I was wondering if it had anything to do with the fact that the a/c automatically comes on when you have the defrosters totally on (still don't understand that system). Please help! Thanks. snipped-for-privacy@yahoo.com
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I've seen exactly the same symptoms on two other car makes.
The fault in both cases is a blown thermal fuse in a resistor network associated with the blower module. (Not a fuse in the fuse panel /boxes)
Checking my Haynes repair manual for the Focus reveals it has the same arrangement.
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.
See <http://www.amacleod.clara.co.uk/focus/
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. My Haynes repair manual suggest that a motor resistor is accessible by removing the blower motor but as I've no personal experience of doing this on the Focus I cannot be sure that it is the module that you may be looking for. Perhaps someone else can advise.
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/products/module.asp?CartID 1227074428657&modul enoG0&Products=9>
or
<http://rswww.com/cgi-bin/bv/browse/Module.jsp?BV_SessionID=@@@@204625928 7.1072511020@@@@&BV_EngineIDcfadckfidfmgicfngcfkmdgkldfhk.0&cacheID=uk ie&3249963877249963877&stockNo69362>
When buying the replacement fuses I've guessed that the one I needed was towards the higher end of the temperature range (150+ degrees C).
On one car the replacement fuse didn't blow again in 6 years (the car was scrapped after that). On a friends car the replacement fuse is still okay after 9 months.
Despite the warnings about not to solder I've 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 :)

I doubt it.
I speculate, it may have been as a result of water getting into the system and the blower motor not running as smoothly as it should. On previous repairs the motor shaft was rusty and some lubrication (engine oil from the dip-stick) was applied to the bearing area.
--
Alan
mailto:news2me_a snipped-for-privacy@amacleod.clara.co.uk
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The reduced fan speed resistor pack has failed- or the multiplug that connects to it. There have been acouple of modded units, but they still fail periodically. Open the glovebox lid fully, then swing it down by pressing the side legs apart and you will then see the resistor pack mounted in the fresh air duct to the heater.
If it is the multiplug that has become toast, Ford do a new plug to bare ends which needs to be soldered and heatshrinked to the existing loom to effect a cure.- DO NOT use crimps or chocolate blocks.
Tim..
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<snip>
DO NOT use crimps or chocolate blocks.

Hi Tim
I'm interested in your advice that crimped in-line connections are not suitable for vehicle use.
I'm an industrial electrical technician, and soldered in-line joints would be a complete no-no in this sort of situation. Crimped joints, properly made with the correct tool, would be acceptable however. I wonder why the difference?
Please note, I'm not challenging what you said as I have noticed before that soldering seems to be the way that the motor industry does things, I'm just curious as to why.
Regards,
Chris.
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As guidence we usually say to the general public not to use crimps in this kind of situation becuase invariably they will not possess the proper crimp tool. By this i mean the 30+ rachet crimpers that you should only use with automotive and industrian crimps to ensure a proper zero resistance joint. In the case of the heater blow resistor etc these things draw afair bit of current (25amps at full chat) and any join thats not perfect is going to heat up and potentially cause a wiring fault behind the dashboard which may end in a burnt out car.
Anyone can use choc blocks and el cheapo crimpers and make an acceptable join but i'd rather not have that on my consience after suggesting it on here. If an individual has the skill to make a solder joint, and understand to heatshrink it rather than insulating tape, they will most lilkely make a much better i.e. safe repair.
Tim..
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" Tim (Remove NOSPAM. Registry corupted, reformated HD and lost alot of

Thanks for the reply Tim.
Yes, I can see the potential pitfalls of DIY repairs here! I've seen the results of "Have-a-go-heroes" squeezing crimp lugs on using ordinary pliers in mains voltage equipment.........!
Chris.
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****FORD RELEASED THIS IN SEPTEMBER 2003**** TSB 03-18-2 Ford Focus 2000-2003 ISSUE: Some 2000-2003 Focus vehicles may exhibit water in the Climate Control Heater Blower Motor Case, which can be associated with an inoperable heater blower motor resistor, blower motor, or a blown blower moter fuse. ACTION: Inspect and seal the cowl area for water leaks when servicing a blower motor resistor, blower motor, or a blown blower motor fuse. Refer to the following Service Procedures. If you hurry this TSB and OTHERS are at this link, (but they only stay up for about 3-4 months. http://www.alldata.com/tsb/Ford/index-post.html
Good Luck!!! --

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