[Eric68]

Hello,


SS 2018. My heating - A/C block does not power on anymore. Nothing, no vent, no heating, no A/C, no temp displays.
I have checked (multimeter) F42 in the engine fuse box and F14 in the trunk fuse box, they are both good.
I have unplugged the battery for 15 minutes, replugged, still nothing.
Are there other fuses that I should check?


Thanks.

[SSgtSS1LE]

One more 40 amp fuse in the trunk fuse block, but that provides power to the blower motor. Use the schematic to check for loose connections or damaged wires. Also, check for diagnostic trouble codes (DTC) to help troubleshoot your problem.

Check for battery voltage at HVAC Control Module connector pin 9.

CAUTION: Do not insert test equipment probes (DMM etc.) into any connector or fuse block terminal. The diameter of the test probes will deform most terminals. A deformed terminal will cause a poor connection, which will result in a system failure. Always use the J-35616-F GM Approved Terminal Release Tool Kit in order to front probe terminals. Do not use paper clips or other substitutes to probe terminals.

[SSgtSS1LE]

HVAC Control Module and K33 X2 Connector:

[Eric68]

Hello, thanks for the diagrams, I've saved/printed them for future use. Where do they come from?
In the end, I've unplugged the battery again and charged it for a few hours because it was a bit low, I noticed that the last time I started the car (I didn't drive much at all during winter), it took some time to start.

Then I plugged it back, started the engine and bingo, the hvac block was back. It's quite strange, because I drove around 80 kms and it was still not working, but the battery was supposed to be properly recharged.

[easttxss]

The pics come from the factory service manual. You can buy a CD version online cheap.