Hi there are blend door motors that control heat and air displacement. These turn cold air on or off when required.
These are located under dash on heater box. They are controlled electronicly and by vacum. Maybe a vacum hose is loose or off the motor for the vents effected.
Sometimes everything is hooked up and working but the motor is just bad. This is paticularly common if the vehicle has ever been in a flood. Good luck. Billymac
Friday, November 25th, 2011 AT 10:11 PM