I have a 04 suburban 1500 LT with the Dual Automatic Climate Control,no matter which button i push,all the air flows to the floor vents instead of the dash vents when i push the one for vent flow,could it be the climate controls or something else,any suggestions?

 

Check your vacuum lines. The doors are vacuum operated.

 

Thanks Joe,are the vacuum lines under the dash where the vents are or in the engine compartment,and if under the hood what location? thanks for listening.

 

Your problem is probably the mode door actuator. They usually fail with age. They are plastic with plastic gears. It is located under the dash. There are different ones that look alike so make sure you get the correct one.