Monday, September 5, 2011

blower motor not running properly on 2003 GMC Yukon XL?

In some cases its faulty motor with faulty controller.Give direct 12 volt by battery to motor and see if its running.If not then its faulty motor.-----

Replace it.But if motor runs then its faulty controller.------ When resistor gets faulty, most of the times the fan runs on high mode, but not on low and medium.But as per your problem , it indicates towards faulty blower module.Check the voltages.What voltages you get, replay.-----------

Customer :--

This is what i get :---

10.5 from red and black(ground), less at 1V from purple/white and black


You can run the blower by back probing the connector and using jumpers from the red to the purple wire and the black of the controller to the black of the motor but thats a whole lot of work.

You are not measuring the 10.5 at the black of the controller right? This is from the purple/white wire to ground?


Good the purple/white is pulled to ground to "turn on" the controller so it feeds voltage to the motor.

The red should have full battery voltage to ground and the black should show full voltage when measured to a full voltage source.

Measure the red to black with the controller unplugged and let me know how much you get when you measure at the battery posts.

It shows 12.5V +/-

And you get the same or 10.5 at the red and black wires of the controller harness?

If it is the same then you need a controller and maybe a blower but the motor would have to be fed voltage to see if it runs normally to verify this.

I have cut off a lead from a controller for this purpose. I'm sure this controller is bad so you could cut this lead to the blower and jump power and ground (doesn't matter which but + to purple is normal) to test this


Thanks expert.I will go for controller and let you know the results.
that will be fine.-----

Great great.Problem solved, it was controller.---------