Please help - 2003 Ford Focus

I have a 2003 Ford Focus and as many people have described my heater switch only works on 1 setting. I have tried changing the heater resister but I am now on my 3rd in 12 mths and even this one has gone
duff too. I am at the end of my tether. Obviously there is an under lying problem. Any ideas?? Could it be the air-con? There is a really bad smell of burning just before it gives out. Please help o I wll have to take out shares in resisters :?
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The underlying problem is probably a blocked pollen filter. The airflow through the pollen filter cools the resistor pack. When the filter gets blocked the resistor pack overheats.
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Paul Giverin

British Jet Engine Website:- www.britjet.co.uk
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First, it's nothing to do with the Air Conditioning.
The circuit for the blower is relatively simple. On the fast setting the fan is straight across the 12V from the battery. On the slower setting a set of resistors lowers this voltage. A thermal fuse protects these resistors (stopping them catching fire) and it is this thermal fuse that goes.
Circuit and photographs at: http://www.amac.f2s.com/Focus1 /
As the resistors are getting too hot possible causes could be:
i) There is some obstruction in the air flow and/or the pollen filter is blocked.
2) Water has entered, via the pollen filter/air intake, and the motor shaft has become rusty and the motor is binding on its bearings.
3) Duff fan motor.
The pollen/cabin filter cover on the early Focus is on the passenger side at the bottom of the windscreen (the seal to the windscreen is part of the cover). To save costs, on some models Ford didn't actually fit a filter element but the holder is still there as it is also the air intake to the inside of the car. If no filter is fitted check for any rubbish that may have entered the air intake.
Be aware that that is not uncommon for an incorrectly fitted cover to allow (rain) water to fill up the passenger foot well. When I removed the cover from my Focus pollen filter one of the plastic clips broke :( I also had to use some rubber sealer on the bit that attaches to the windscreen.
For motor problems you will have to remove the fan assembly. If the problem is a rusty shaft, and if you can get to the bearings, a few drops of oil may be all that is required. Don't use something like WD40! Use a decent thicker oil engine oil and apply one or two drops, using the dipstick, to each of the bearings. Make sure that the fan spins fairly freely before re-installing.
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Alan
news2006 amac f2s com
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