Quote:
Originally Posted by Westie
You are partly correct here. The supply side of the blower motor is always switched via a relay no matter what the speed setting is. The return or ground side of the blower motor is either switched through a resistor or combination of resistors for the three lowest speeds, but it is switched directly for the highest speed.
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Yes, you are correct. My mistake (I had my mind on cooling fan relays for some reason)
Most heater fan circuits works like this;
the fuse supplies battery voltage to the heater-a/c fan relay, the relay provides voltage to the fan motor directly after a 'mode' is selected (ie-vent position). The fan switch then directs the voltage ground for the fan motor thru the resistor pack (or module) in all positions except "off' (ground circuit open) & the 'max/high' position, which is run directly to ground (via the switch).
Sorry for the confusion.
& thank you Westie for the correction.