Interior Blower Motor Not Working...help diagnose?

[Patrick C]

Hi gang. For the past few days my blower motor has been sporadic. Either working at all 4 speeds, or not working at all. Now it will not work at all.

My findings so far:

I can hear the relays click on speeds 3 and 4, but the fan doesn't blow. The fan also does not blow on speeds 1 and 2.

I hooked a lightbulb up to the 12v and ground wires at the fan and the bulb does turn on when I change the fan speeds, so I know power is getting there.

I replaced the blower motor with a brand new spare that I have, and it still will not blow.

I have checked the resistor and it appears to be okay. Slightly rusty, but I cleaned it up and it still will not work.

Any ideas??

[NightFlyer]

Hi gang. For the past few days my blower motor has been sporadic. Either working at all 4 speeds, or not working at all. Now it will not work at all.

My findings so far:

I can hear the relays click on speeds 3 and 4, but the fan doesn't blow. The fan also does not blow on speeds 1 and 2.

I hooked a lightbulb up to the 12v and ground wires at the fan and the bulb does turn on when I change the fan speeds, so I know power is getting there.

I replaced the blower motor with a brand new spare that I have, and it still will not blow.

I have checked the resistor and it appears to be okay. Slightly rusty, but I cleaned it up and it still will not work.

Any ideas??

Do the motors spin if hooked up directly to a 12V power source?

As you've confirmed that relays and resistor are good, I'd be inclined to look at the rotary switch next - seems like these have been failing lately.

Best luck :thumbup:

[Patrick C]

Do the motors spin if hooked up directly to a 12V power source?



Yes.

[NightFlyer]

Yes.

My guess is that the rotary switch isn't passing on enough power to turn the motor.

You could try jumping the switch to confirm.

Otherwise, I'm at a loss, as everything else in the circuit appears fully operational.

[NightFlyer]

Just wanted to also mention to check the circuit ground, if that hasn't already been done (I guess I assumed that it was given the general state/condition of your car) :wink:

[Patrick C]

My guess is that the rotary switch isn't passing on enough power to turn the motor.


I wouldn't think this could be an issue, especially on speeds 3 and 4 when the relays are clicking?

[hmcelraft]

I would check to see if the motor works out of the car - directly to power & ground. Check the grounding of the motor in the car. Check for power to the resistor - looks can be deceiving. Make sure it is OK. With the relays activating it is probably not the fan speed switch. Remember speeds 1 and 2 are fuse powered and 3 and 4 are circuit-breaker supplied. Speed 4 is not through the resistor - it is a full power circuit through the relay. With no speed 4, I am suspect of the grounding.

[Patrick C]

Ultimately, where do the grounds from the blower motor go? Is that a junction behind the driver side wheel to the frame, or is it somewhere else?

[Patrick C]

Harold hit the nail on the head! The issue turned out to be I needed to sand away the paint on the blower motor so that the 3 pronged connector that screws in could be touching bare metal. Once I did this, I hooked everything up and it was blowing strong!

Thanks for the help. Keep your fingers crossed that this was the issue and that it stays working!