HVAC ISSUE

psbowler · August 20, 2017

I am having trouble where when running the heat, it stays warm until truck reaches operating temp and then starts blowing lukewarm air out of all vents. Now, when running the AC, it only works for a few minutes and then hot air comes out of all vents. There are plenty of posts on the internet about air door actuators, but most are suggesting that rarely both passenger and driver actuators will fail concurrently. Therefore, could it be the control module, which would be an easier fix as some of those actuators are almost impossible to reach? Additionally, the air blowing in the back seat is the same as the front if that helps.

Thanks.

O_J_Simpson · August 20, 2017

Help us help you. Since we have no idea what truck or climate control system you have how can we even start to help?

tramz · August 21, 2017

Start with the Air temperature actuator.

psbowler · August 21, 2017

Sorry about that. It's an 04 Silverado with automatic climate control.

txab · August 22, 2017

You might try the HVAC recalibration procedure:

Disconnect battery cables or...

Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
Re-install the HVAC/ECAS fuse
Turn key on, but do not start. Make no adjustments to HVAC controls at this time
Let any adjustments happen on their own
Wait 40 seconds for the HVAC control module and actuators to re-calibrate.

I've always had the best luck at this point by turning key off. Removing key and closing the door. (Signals the BCM of a completed driving cycle)

Then climb in in, start and drive.