Try a "reboot"!
Remove a battery terminal for 10 minutes, then reconnect.
Turn ignition switch to on, but don't start.
Wait 1 minute.
DO NOT touch any buttons in the vehicle during this minute.
Then start vehicle and let idle for 5 minutes.
Drive above 45 mph as soon as possible.
This "reboots" all the computers in the vehicle including the A/C which then "resynchronizes" the actuator doors during the power-up.
This also reboots the engine computer and the idle and driving above 45 mph helps it to "regain" its operating memory.
If this does not work, you would need a GM Factory Service Manual set which would have complete troubleshooting instructions for this problem as well as complete part replacement procedures. Order from helminc.com or a GM dealer.
You would also need to know how to use a multimeter along with the instructions in the manual. How to use a multimeter...
http://www.google.com/search?hl=en&s...imeter&aqi=g10