Blend door controls the air temperature. Mode doors control where the air goes.
If you cannot select hot/cold it is the first one, If you cannot select floor/dash/defrost it is the second.
In the case of an F150 you have a total of four vacuum actuators. One controls the fresh air/recirculate, one controls temperature and two are mode control.
All can be tested with a hand held vacuum pump at the back of the control panel.
Tuesday, April 20th, 2021 AT 9:35 AM