2006 Mazda 6 heater blower motor quit working

FURB1593

MEMBER
2006 MAZDA 6
3.0L
6 CYL
AUTOMATIC
78,000 MILES

I checked all the fuses and relays, uninstalled the motor put 12 volts in it works correctly, when in the car doesn't work on any speed (car has auto air) should my next step be the replace the resistor? Or am I missing something else when I turn the speed up the digital display shows each step on going up and down any help would be greatly appreciated thanks Jeff

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

You only have a heater resistor when you have the old and reliable three or four-position switch. With the electronic controls that the engineers seem to think everyone wants, there is going to be a power module that uses "pulse-width modulation" to vary the motor speed. They use a high-power switching transistor which is very prone to failure in that application.

Pulse-width modulation, (PWM), means the motor is turned on fully, then off fully, hundreds of times per second. The ratio of on to off time is varied to vary the average voltage, and therefore the speed. I'm sorry I can't tell you where that module lives in your car, but chances are you'll find it if you follow the motor wires to it.