Bredd1

My a/c blower stopped working in my 2007 Base corvette. It was working fine one day then the next day I get in the car, no air from the a/c. After reading other threads I figured that the blower motor may be bad, I ordered a new one from Rock Auto, it came today, I installed it but its doesn't work either. I tried testing the control circuit, I'm getting 13 volts between the black and red leads but not getting anything on the blue lead in the middle on the connector. Not sure if there should be voltage there or not, tried adjusting the control to high and low but nothing on the blue lead. Any suggestions?

Bredd1

Oh, I did check the fuses prior to ordering the new blower motor.

Bredd1

OK, I tried replacing the blower motor, checked all the fuses, and replaced the head control unit (eBay). I did some checking with the volt meter and found that I'm getting voltage 13+ volts between the red and black lead, I do not getting any voltage on the grey wire in the middle of the connector. I found another CF post that had a partial diagram and it showed that the grey wire is for the blower speed control. Does anyone have the full print for the a/c control circuit or know how the speed control circuit work?

4SUMERZ

Here is the electrical schematic. Is it possible that the HVAC control module (in the console) has a bad solder joint or is faulty?




As a further note, you may want to check the connector pins for the HVAC control module (especially the GY/BK)
I looked at the diagnostics for blower motor inoperative, and it's one of 3 things:
1) HVAC module faulty
2) Connector wiring for the HVAC modules
3) Blower motor

4SUMERZ

Here is the HVAC Control Module connector and pin layout

Bredd1

Thanks, I've tried replacing the motor and HVAC module already, there is only one thing left and that's the wiring. I'm going to try and check that today. Do you know what kind of signal passes through the grey wire, 12v+, 12v-, 5v+, 4-20ma?

Bredd1

Ok, I just checked the wiring for the HVAC module and everything was good, I also checked continuity of the gray wire from the module to the motor and it is good. I'm at a lost at this point, I've changed the HVAC module with one I purchased on eBay, I replaced the motor with a new one, and I've verified the wiring. Any other suggestions? Only thing I can figure is to try another HVAC module.

4SUMERZ

It's a rheostat type of control, so measuring voltage at the blower motor (+ lead and - lead) would likely change with the speed selector.
The manual doesn't indicate any voltages, just uses a scan tool (pulses), and a test light for indicating voltage.
Here are the other connectors for the HVAC control module and the blower motor.

I can send you the troubleshooting section if you want it. PM me your e-mail and I'll send it to you.
That's about all I can do to try to help you.
Hopefully, it is either a pin connector, wire or ground causing the issue.

4SUMERZ

info sent via e-mail

Bredd1

Thanks! I've exhausted everything that I can try without the specialized Tech Scanner and tools. I'm going to make an appointment and take it to my dealer. I'll let you know how it comes out.

4SUMERZ

Thanks. Hopefully it's something easy to fix.

Bredd1

Ok, I took the car to the Chevy dealership this past Friday, they did service and figured that the blower motor was bad, I explained that I had replaced the motor, they were insisted that the motor was bad so I asked them to go ahead and replace since I was there. They came back said that they did not have one in stock so I just asked them to put it back together and I would contact Rock Auto and have them send a replacement and I would change it myself, still had to pay Chevy $125 for their diagnostics. I contacted Rock Auto and they sent me a replacement that I received today and install it, it did not work. I've checked everything on the car and everything seems to work and points to the motor being bad but its hard to believe that I've tried two different NEW motors plus my original motor and none of them worked. I used an oscilloscope to verify the PWM signal for the motor speed control and it worked and varied as it should and I have 12 volts going to the motor. Don't know what else to do!

4SUMERZ

Sorry to hear about the diagnostic from GM that didn't fix anything

Here is what i would do to start with, just to prove that the fan motor is OK.
Connect a single 12V DC wire and single ground wire from the battery directly to the motor. That should make the blower motor run if it's getting positive 12V and has a good ground connection.

With the motor proven to work, and everything else that has tested OK, then it has to be a wire or pin connector that is bad between the HVAC contoller and motor, or a bad connection for the ground.

Good Luck with resolving the issue.

RICH 28

I hope you figure it out.

TONYS68L36

Have same issue- any update?

Bredd1