04 keeps dying overnight

[gtoguru]

The HVAC system has actuators that control the hot/cold and inside/outside air that go bad and can cause the battery to go dead. They have power on them even with the ignition switch off. Just had that problem on my wife's Impala. Bad design from GM.

 

[PatDTN]

The HVAC system has actuators that control the hot/cold and inside/outside air that go bad and can cause the battery to go dead. They have power on them even with the ignition switch off. Just had that problem on my wife's Impala. Bad design from GM.

Hm. Yeah I hear mine twitching any time I open the door on my '09 Tahoe. What should I be considering to fix that?

 

[gtoguru]

Hm. Yeah I hear mine twitching any time I open the door on my '09 Tahoe. What should I be considering to fix that?

There is a procedure to recalibrate them and if that doesn't work
the faulty actuator has to be replaced. There are 3 of them that usually go bad. Inlet air actuator behind glovebox and hot/cold actuators under dash, one for each side. The one behind the glovebox is not easy to replace. These are continuous turn motors and the dash controls tell the computer how to position them. If one of the gears in the actuator gets a tooth broken it will keep trying to set its position and will never turn off. That's how you get a dead battery

 

[JetBlackNali]

Had this exact problem 2 years ago. Ended up being a dead cell. Would test well and randomly not start. Ended up replacing battery with an agm type battery and all has been well for two years. Also local distributor for optima batteries said to stay away from them. Quality has slipped since new ownership.