HVAC Blower Not Working

Tiny
MATTATO1
  • MEMBER
  • 2007 PONTIAC GRAND PRIX
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 275,000 MILES
I have a unique problem. End of summer blower for the climate control stopped working during a hot summer day last year. It was just for a moment and started back up after an engine restart. It was fine for 2 weeks, then it happened again. But this time for a little over a week. Came back to life on a lunch break. It was fine for 2 weeks, then it stopped running again. Never came back. I checked all my fuses. The are fine. Even replaced the HVAC fuse anyways. I replaced the blower resister to no avail. I had the blower tested and it was fine. I changed it anyways. No go. I returned it the AutoZone. All the climate controls work. If I turn on AC, the compressor turns on. If I change the vents to defrost and other positions, it works fine. Just no air. Heat works, just no air. You can hear the diverters working. Fresh air will deliver a little heat when I'm moving. The blower will not start. At my wits end. I need heat. It's cold. I cannot find any other forums online about this specific problem. Next step is to replace the control module. It's a manual control unit with no heated seats. I cannot find any cheap brand new. Please help!
Wednesday, February 9th, 2022 AT 3:57 PM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Maybe I missed it, but have you confirmed the blower motor itself is okay?

We do this by putting 12 volts to the blower motor and see if it turns on.

Here is a guide that helps with this issue:

https://www.2carpros.com/articles/low-or-no-air-flow-from-vents

What I would suggest you do is remove the connector from the control processor (resistor) with the key on and blower motor on, and jump pin E to pin D. Or you can go to the back of the blower motor connector and jump A to B, but you will need to have it plugged in and the blower motor turned on to do it this way.

This forces 12 volts to the motor. If it comes on, then the blower motor resistor (control processor) is the issue. However, I suspect it will not come on and you will need to replace the motor.

https://www.2carpros.com/articles/blower-fan-motor-works-on-high-speed-only

Please see the wiring diagram below. Let me know what questions you have.

Thanks
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Thursday, February 10th, 2022 AT 4:41 PM
Tiny
MATTATO1
  • MEMBER
  • 2 POSTS
The blower motor does run. I took it to a shop, and it tested good. It is also a brand-new resistor. I am thinking the climate control module is bad. It's the only part that hasn't been replaced or tested.
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Thursday, February 10th, 2022 AT 5:09 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. If you want to confirm it, go to the resistor, and check the power on the purple wire with the fan on. You should have 12 volts all the time on this wire but just turn the fan on to be sure.

Then check the voltage on the gray/black wire with the fan turned to high. You should have 12 volts on this as well as this is your speed control.

If you are correct, then you are not going to have voltage on this gray/black wire which means the module is not sending the voltage.

However, we need to confirm these two in order to be sure because if the resistor is not getting power on the purple wire, then it will not work. Then it is possible (unlikely) that you have a faulty new resistor.
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Thursday, February 10th, 2022 AT 5:59 PM

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