94 sierra a/c problem

I have a 94 sierra that when i turn the air on it will only blow out the defrost or the floor, im thinkin it might be a vacuum problem but not sure. Does anyone have any idea where i should look or what i need to do to fix this problem? Any help is appreciated. Thanks, Steve

I have a 94 sierra that when i turn the air on it will only blow out the defrost or the floor, im thinkin it might be a vacuum problem but not sure. Does anyone have any idea where i should look or what i need to do to fix this problem? Any help is appreciated. Thanks, Steve

The mode door (directs air out the vents or defrost or floor) is controlled electronically by an actuator. It located near the gas pedal above the tranny hump. They can be purchased at any AC Delco parts store.

They wear out and become too weak to move the door. Sometimes the arms break but there would be parts on the floor if that happened.

//2000CAYukon

I checked it out and found the motor was working but the linkage had come apart. Thanks for the help.