Blend Door Actuator
A small electric motor that turns the HVAC blend door to regulate air temperature in the cabin.
The blend door actuator is a small, electronically controlled electric motor containing plastic gears that operates the temperature blend door inside the vehicle's dashboard HVAC housing. When you adjust the temperature control on your dashboard from cold to hot, the climate control module signals the blend door actuator to rotate.
The actuator turns the door, adjusting how much air flows through the air conditioning evaporator core versus the heater core, mixing the air to achieve the desired cabin temperature. Inside the actuator, the tiny plastic gears can strip or break, or the electric motor can fail.
Symptoms of a bad blend door actuator include the air temperature remaining stuck on all-hot or all-cold, clicking or clicking noises behind the dashboard when changing temperature, or different temperatures blowing from driver and passenger vents on dual-zone systems.