heater problem on 1999 Chevrolet 1500 Pickup

my vent wont switch to defrost or any other position all functions work ac heat just wont switch from vent where are actuators located at on this truck

Asked by for the 1999 Chevrolet 1500 Pickup
Typically the direction of air flow (defrost, dash vents, floor) is controlled by a vacuum motor. Check around under the dash for broken or disconnected vacuum may help.
1 more answer
electic motor for heater door i can not think of name of part bleed actulater motor 39.95 go to heater parts