Hey guys, I am willing to bet there's going to be a lot of people stumped like me on this one. The other day I took my truck in to have the blower motor replaced, since it wasn't blowing any air unless I was in motion. Never blew hot though. The garage tested and determined the ECU or ECM was out, whatever tells the blower which speed to blow, which brings me to my issue. Now I have heat which I am very grateful for since it's starting to get cold outside but for some unknown reason I only get heat coming out of the passenger side vents!! All vents are blowing now, but the drivers side vents (all of them) only blow outside temperature air. I am bamboozled! I asked the garage that replaced the unit and they had no idea, ASE Certified mechanics had NO IDEA! Somebody help! lol. Oh if it matters, my truck is a 05 1/2 Ton Silverado with the Vortec 5.3.
sounds like you have the electronic auto control ac system. with dual temp controls.
the temp door motor is most likely defective or stuck on the driver side.
replacing the AC computer controller may have been unnecessary. next time disconnect the battery ground turn ignition to on for a few min. then off then reconnect the battery ground. sometimes the computer needs to be power reset.
As j cat said, the temp doors will get mis-aligned sometimes when the battery is disconnected. They are supposed to reset themselves, but don't always. Try disconnecting the battery and reconnect it, try the heater, if it still doesn't work right, move the temp control and try the reset again. I've had to do it 3, or 4, times before it would reset.
If you can not get it to reset, the door motor will need to be replaced.