Heater issue

[SnowDrifter]

You may also need to have a "calibration" updated on your HVAC control unit (which would be a programming update done by a competent shop or the dealer). I don't know if you have the manual HVAC or the AUTO HVAC, but it might be worth checking into. IIRC @SnowDrifter had it done recently.

It's super easy

Pull the HVAC fuse from the underhood fuse box

Take a whiz

Put it back in

Start the car and like... Don't touch it for a minute or two

 

[Fless]

It's super easy

Pull the HVAC fuse from the underhood fuse box

Take a whiz

Put it back in

Start the car and like... Don't touch it for a minute or two

Well, maybe it wasn't you. But I thought someone here recently had the programming (calibration/firmware) updated by someone with a scan tool and access to GM software. I could be dreamin'.

 

[SnowDrifter]

Well, maybe it wasn't you. But I thought someone here recently had the programming (calibration/firmware) updated by someone with a scan tool and access to GM software. I could be dreamin'.

Oh yeah that was also me

But would need to verify codes / go down the diagnostic tree to validate you need it

I ended up having the local dealer do it

 

[houstontaylor]

My 2003 Tahoe mode door actuator ( the blend door contols temperature) went out and it only blows against the windshield. After looking at all the youtube videos and removing front panels I looked with a scope under the dash on the driver's side and could see the actuator out of the normal range but trying to move when I change the control, so it's probably a broken actuator gear per online videos and an above comment. The replacement actuator was in stock at Autozone. Now I just need to figure out how to contort myself to pull out the old actuator without the plastic cam, realign the cam, and install the new actuator. Not sure I can do it. A person on one video gave up and just manually set the air flow to straight out.

 

[crazydatsun240Z]

There are 4 actuators up front and 2 for the rear AC. You really need a bi-directional scan tool that can read BCM codes and interact with the actuators to test them out.

Without the Tech-2 type tool, we're guessing. My guess would be the Recirc actuator is either not closing all the way, bleeding off volume and cool air or the foam material on the door has started crumbling leaving a gap causing the same conditions. If the rear is always cold but does cycle through the modes, that would be the auxiliary temperature actuator.

The actuators are like servos on radio controlled airplanes and such. Inside the box are plastic gears and these usually crack causing them not to work right anymore. Some folks glue them back together and the repair is a success. I didn't want the down time when doing mine, just replaced them with new GM ones.

Just wanted to say thanks to this thread & @swathdiver as I was having problems with an actuator myself and this helped me out, mine turned out to be something stupid with the actuator mounted in the front left passenger footwell area. ( my daughter throws in her huge backpack in , on the floor everyday and I guess one day last week it hit the plug right on the release clip just so..and then it came out of its socket and I lost A/C . Glad it was the easy access actuator this time but I can hear a gear issue on the drivers side that is going to have to be dealt with soon. Again thanks.