Mechanics

HVAC CONTROL MODULE QUIT WORKING

1992 GMC C2500 • 226,000 miles

The electronic hvac control module in my truck just shut off driving. I replaced it with one from the salvage yard, didn't fix it. Used a volt meter and tested power wires, the battery and ignition power are fine. The main ground shows good but the second shows bad. Don't know where this ground goes or if it even if it would effect the module. Hot here and don't have a/c.
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Zpainter1015
August 28, 2011.




The ground could be under the dash. I would recommend running a new one.

Ran a new ground module came on and worked. Then smelled a burning smell and blower quit and won't work on any setting. The blend arrow lights are also now flashing.

Tiny
Zpainter1015
Sep 4, 2011.
Check to see if there is power to the blower motor. There must be something causing things to overheat. The original ground may have melted.

Had the old control module out of truck so put it back in and blower worked for a little while then quit. Found on circuit board that one of the connectors is burning the solder. It's is a black wire in slot 9 on connector. Wiring diagrams don't show any wire there.
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Tiny
Zpainter1015
Sep 6, 2011.

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