Q: Heater only blowing hot air and cannot adjust controller to change

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Heater will control not working

My car has 190000 miles.
My car has an automatic transmission.


You likely have a problem with the ’blend door’ which turns the air from hot to cold. There is also an actuator motor which turns the door from hot to cold. And finally, it may possibly be the knob which is causing the problem.

From my experience the blend door is usually the cause. The shaft breaks so that the actuator motor cannot move the door. To repair this problem requires dash removal, coolant removal, refrigerant removal, and a lot of repair time. The motor could also be inoperative for the door which is an easier repair. I have also seen things fall into the vents blocking the door.

Diagnosing the problem is the first priority. A qualified technician, such as one from YourMechanic can diagnose your heater control issue and make the repairs needed to have this problem resolved.

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