2003 Silverado A/C Problems

[amoe04]

The A/C on my '03 Silverado acts unusual. It blows from the floor vents and the defrost. If I play with the controls on the dash I can get it to "stick" in the normal position. If I am traveling on the freeway at consistent speeds it will stay in the normal position. When I am driving on roads, with stop and go driving, it blows out of the floor and defrost vents. The A/c also blows hot on the passenger side.

 

I have replaced the dash control and that did not help. I also heard that disconecting the battery and reconnecting it may help with the hot/cold issue on the passenger side but that did not help either. My last thought is that it could be vacuum lines but I am not able to spot any running through the firewall.

 

Any suggestions?

 

Thanks

[GM-Tech]

There are no vacuum lines. The doors are all controlled electrically. Sounds to me like you have a bad actuator. The a/c tests these each time you start up and if it sees a door position that it doesn't like, it'll set a code and the actuator will move to it's default position. This is defrost for the mode actuator and hot for the temp actuators. It's unusual to have to different problems at the same time though.

 

Try disconnecting the battery again. Make sure that when you start the truck after that, DO NOT touch the a/c controls for at least a minute while the control head goes through it's initialization procedure. It'd take to long to explain the why, but sometimes you have to do this initialization numerous times before it gets it right.

 

Otherwise, this needs some diagnosis with a scanner that can see what's going on with the a/c doors.