Demist blower IS NOT WORKING - 2001 BMW 5 Series

Instrument panel fuse block is usually near the driver side kick panel or between it and the lower steering column .

What make model an year vehicle ?

check that the inlet defuser is moving to allow air into the blower.

check the blower motor for power and ground at the motor. if this is good hit the blower, if it starts or tries to start replace the blower motor. if you have no power at the motor check the resistor for power going in and a good ground. if you have these going in and not coming out then the resistor is bad. this is a common problem with just about all cars.

the actuator the changes the vent flap position is not working. Check vacuum hoses or module.

demister? ah rear defogger (glass heater), (thanks wiki)
it's also and option.

what car, what year. all are diffreent.
pre 96 is here. (my work)
21 is just to right of dash dimmer pot. 46
http://www.fixkick.com/ECU/92-95-dash-parts.JPG

There are very few 20 year old Corollas around, but by chance I passed a 1989 car which was going green with moss parked under a tree for a couple of years. I got permission of the owner and removed the heater unit, and fitted it. It worked first time. It is a credit to the build quality that it worked.

All that was wrong with mine was the fan had got very dusty and had stuck. I could have put the original unit back, but the "newer" one was in much cleaner condition. I've never done this sort of job before so it took me a whole afternoon. However, an experienced person who did this before would complete the job in about 45 minutes.

Check rear demister control relay operation,
Check for presence of 12V power (and ground connection) at rear window heater connection.

Check continuity of the rear window heating element.

ONE OF THE HEATER DISTRIBUTION FLAP MOTORS FAULTY.UNSCREW GLOVEBOX AND YOU WILL SEE THE ONE THANS NOT WORKING(TURN ON BLOWERS TO TEST)

EASY FIX HAD SAME PROBLEM WITH MY AUDI A4 2002 JUST LAST WEEK.....WILL BE ONE OF THE CONTROL MOTORS FOR AIR FLOW...UNSCREW THE 4 OR 5 SCREWS THAT HOLD THE GLOVEBOX IN PLACE TAKE CARE TO UNPLUG GLOVEBOX LIGHT WHEN LIFTING OUT...NOW YOU WILL SEE ALL THE CONTROL MOTORS RIGHT-HAND SIDE OF YOU...EACH ONE CHANGES THE AIR FLOW ...THE ONE FOR THE WINDSCREEN IS THE ONE NEAREST TO THE FRONT OF THE CAR..UNPLUG THE WIRING CONNECTOR UNDO THE 2 SCREWS NOTING HOW THE MOTOR SHAFT ENGAGES...EASY....IF YOUR UNSURE WHICH CONTROL MOTOR IT IS TURN ON YOUR BLOWERS AND TEST EACH ONE..SIDE VENTS, DEMISTER,ETC...TRY AND GET A SECONDHAND CONTROL MOTOR FROM SCRAP YARD...DEALERSHIP PRICES JUST A JOKE.. FOR A CHEAP TINY MOTOR NOT MUCH BIGGER THAN A MATCH BOX OVER A £100 SCRAP YARD £5 POUNDS...........HOPE THIS WILL BE OF SOME HELP TO YOU...