HVAC has no power

MOJOZRIDE

MEMBER
2005 CHEVROLET MALIBU
V6
2WD
AUTOMATIC
189,000 MILES

It started last summer when the A/C would be running fine, then I would hit a bump, and randomly it would completely stop working. Then sometime later, I would hit another bump, and it would start working again. It would go long stints of time without working, but I would randomly hear a short "zit zit" sound (like wires shorting out or an air leak or something) coming from the HVAC region. This fall the HVAC stopped working altogether. Then one day, I went to start my car, and the heat and defroster worked just fine for about a day, then nothing again. But what is weird is the rear window defroster has continued to work, even though the control switch is in the HVAC module.
So we took it to a dealership, they said it needed a new HVAC control module for $900.00 (part and labor). We thought we could beat that price ourselves.
So now my husband has checked all the fuses, he has replaced the relay, the resister, yet the blower motor is not getting any power.
Today we replaced the actual HVAC control module for $350.00. But the dealership was wrong, it did no fix the problem, we still have no functioning heat, front defroster, or A/C. But The rear window defroster works like a champ. The unit and blower motor still has no power, and we cannot figure out why. We are at our wits end. Please please please advise.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,913 POSTS

Hi,

When you say there is no power, are you referring to the blower motor itself or is there more to it than that?

Let me know.

Joe

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Saturday, December 14th, 2019 AT 10:07 PM

MOJOZRIDE

MEMBER
2 POSTS

Hi there, The entire HVAC unit does nothing when you turn the knobs. The only thing on the HVAC module that works is the button to turn on the rear window defroster. It lights up and works.
My husband is the one working on everything. He has replaced both the relay and resister, and left them in place. We hoped that the HVAC module would begin working with those changes. It did not. My husband kept saying, "why isn't there any power to the blower?" Even with the continuity tool, it wasn't making sense. So we ordered a used HVAC module. That didn't work. Then we ordered a brand new HVAC module. That didn't work.
Now we keep coming back to that question, "why no power to the blower motor?"
So we welcome any suggestions.