How to know if Blend Door Actuator is working

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The blend door actuator is a device that is in charge of controlling the flow of air and temperature in your vehicle.

 If you notice that your car is releasing cold air and you are finding it difficult to change the flow of air then, you might be dealing with a faulty actuator.

You need to be able to access the blend door actuator properly to be sure that it is truly broken.

Depending on its settings, the actuator controls the air temperature and direction. You can use it to set temperature, defrost, fresh air, mid vent, and so on.

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The passengers in the car can control its temperature and set the direction of the air.

Here is the highlight of the topics you we will discuss in this post:

  • How to know if blend door actuator is working
  • Where is the blend door actuator located
  • How does the blend door actuator work
  • How to test blend door actuator
  • Chevy blend door actuator reset
  • Does the blend door need to be open or closed for heat

Where is the Blend Door Actuator Located?

The vehicle climate settings control the blend door actuator. A passenger can open and close the door at various positions to either block or allow the passage of air.

This is done so that the vehicle will have its desired temperature. The location of the blend door actuator is usually close to the evaporator and heater.

The blend door is built with a plastic housing, a plastic gear, and a small electrical motor. In addition to that, it has a sensor that works with the climate computer by sending it information.

The blend door actuator controls temperature (hot and cold) settings for the passenger compartments in a car.

The car has a computer that sends a command to the blend door actuator so that it will start rotating the actuator motor and change the direction of airflow.

The direction it goes depends on the temperature chosen by the driver or the passenger on the climate control system.

The actuator is like a motor that has a different sensor that connects it to the climate control system of the vehicle.

An actuator is a technology that is in a small box. It has lots of electronics, plastic gears, and case.

How Does the Blend Door Actuator Work?

The blend door actuator is a very important part of a vehicle. It is like a car’s electric motor built from plastic gear and housing.

It also has a sensor that sends back information to the climate system in the car. Once it does that, it moves temperature and air towards the heater plenum.

The plenum is responsible for controlling the settings which include defrosting, recirculation, fresh air, floor, mid vent, and so on.

In addition to this, thee actuator is useful in controlling the cold and hot settings in different compartments inside the car.

The climate control system in the car will send a command to the actuator. Its motor will start moving so that it can change the direction modes of the air.

The direction it moves will be according to any temperature that is chosen by either the driver or passenger. It is usually chosen on the climate control systems.

Car systems mostly have about 3 or 4 units placed in areas surrounding the HVAC plenum. This will vary according to the model of the vehicle.

How to Test the Blend Door Actuator

You can test your blend door actuator if you are running the engine and you unable to get heat. You can choose to recalibrate the heater or simply replace the blend door actuator.

Most actuators use electrical motors to change the flow of air and the temperature of the air.

They do this by opening and closing that heater box flaps that are under the dashboard.

Once the battery has been disconnected or is dead, you can start to work on your car. If you are finding it difficult to change the temperature in the car, the solution might be to perform a recalibration.

You can take your car to a mechanic if you have no idea on how to do a recalibration. The problem might be that you have a bum blend actuator if the heater is blowing cold air.

For confirmation, you should check if the heater hoses are hot. Once you find that out, you can fix it as fast as possible.

The cost of a new actuator is about $100 and it usually comes with its manual. Once you have the manual, you will need screwdrivers, and a ¼ inches drive socket set.

There are actuators that control the blend door and mode door; you will need to identify it using the manual.

After doing that, check underneath the dashboard and find the actuator. It is usually placed on the heater box.

You will need an extra person that will switch between different modes and temperatures while you keep watching the actuator underneath the dash.

If the actuator does not move as the switch goes on, then it is faulty. Another possibility is that the door or linkage might be faulty and not the actuator.

If this is this case, you will need the services of a professional to replace it.

Does the Blend Door Need to be Open or Closed for Heat?

Well it doesn’t matter whether blend door is open or closed as long as the car engine is running, the coolant will always move to the heater.  The actuator has a shaft that rotates on a heater box door.

It does this so that the air passing to the heater will stay regulated. A low temperature means that only a minimum of airflow will get to the heater core.

The remaining will pass around it. The actuator blends a little air inside the vehicle with hot air that is from the heater.


In summary, this post has explained some of the ways you can know if your actuator is working or not. Unless you have the knowledge of fixing an actuator, it is best you take it to a professional.

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