The heater blower does not work at all, even in the high switch position. But in the high position, and only in that position, there is a constant humming sound from the heater relay. I have tested the blower motor which is ok, and a repacement heater relay did not change the situation. The blower resistor is probably defective, as the blower only worked in the high posistion for some time, but now there seems to be an additional problem.
Its cold in Norway. Any suggestions ??
did you check the fan switch on the dashboard
If you cant get it fixed in time for the cold weather, hot wire the blower via a heavy swirch so you at least have the facility.
Have you checked the 'heater' fuse, paying attention to its socket looking for overheating. These fuses pass heavy current and can overheat the socket due the high current and then go resistive.
Apart from that, I'd get a w/shop manual as there are quite a few variants in this area depending on whether the car has climate-control or simple AC.
From my circuit it appears there is a power-transistor which controls the medium speed of the fan. A resistor is used to give low speed but is also in circuit for medium, so you are may well be on the right track.
The actual blower speed switch does not pass the motor current, but all the same ehould be tested with a digital-ohms meter on a low range.
Jason
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