Blower motor will not turn on.

JOHNJANSEN

MEMBER
2004 PONTIAC GRAND PRIX
190,000 MILES

And month ago the blower motor would not turn off when car was off (key out of ignition). And was on high. I replaced resister module and it worked for a couple of weeks. Wife complained motor was speaking although I never heard it. Now blower motor won't turn on at all. I had AC recharged a couple of days ago. I'm thinking the motor needs replacing. It's a used one I put in a year or so ago. What do you think? Thanks!
1

1 Reply

RACEFAN966

MECHANIC
5,029 POSTS

Within the A/C control panel is a logic board that is always hot. It is supposed to control the blower motor. It probably has some circuit board level issue and there is no way to test it. If you had the switch off and the blower was still running. The switch itself could be bad. The diagram for the circuit is pretty simple. However it is hard to detrmine if there is a way for the blower motor to be enrgized with the switch in the, "OFF: position if there is a logic board failure. This is because there is a controller for the blower motor is part of the logic board controller and is hot in start or run. This means that if you bought the logic board it is integrated at a circuit board level and would be part of it, meaning it does not show any connection so it is saudered in the logic board.
I would rule out the resisotr as it would have to be hot to run the fan and as you can see in the diagram it is probably something, I attached wiring diagram, that is in the logic board that is bad.