99 Tahoe LS, 5.7 engine. I just changed my mode door actuator and it did not solve the problem of no air conditioning out of the main vents. The actuator was the one closest to the gas pedal. It will not blow out of the vents but it will blow out of the defroster,However I discovered that if I turn the AC off I get plenty of air out of the main vents. Do I need to change the blend door actuator? Thanks for any help.

 

Did you "train" the computer to recognize the new actuator? If not look online.

When I installed a new actuator (passenger side, under dash) on our 2005 Yukon, had to go through process so computer could learn its position.

 

Do I have do a reboot as they call it?