Heater Control Valve – What is It? How it Works?

There are different parts in the air conditioning systems of vehicles. And they must very well for a working and effective air conditioning system. If you have one of these systems in your car, you probably have a heater control valve. Here, we talk about the heater control valve applications that are common in most vehicles. And you will learn lots of things about them.

What is Heater Control Valve?

Heater Control Valve

The heater control valve is a very basic valve that controls the hot liquid that comes to the hater core of the air conditioning system of your car. In a basic air conditioner system, there is a heater core that the fresh air passes on it. And the temperature of the fresh air increases. After that, the hot fresh air comes to the cabin of the car.

So the level of heat inside the heater core defines the heat of the fresh air that comes to the car cabin. The heater control valve is the system that controls the hot liquid that comes to the heater core. And once you adjust the temperature of the air conditioning system from the knob on your car, you adjust the heater control valve to adjust the amount of liquid that comes to the heater core.

So this is the general working principle of heater control valve applications.

What are the Common Problems with Heater Control Valves?

There can be some problems with the heater control valve system of your car. If you know these problems, dealing with them will be very easy for you.

  • Leaks: In general, leaks are the most common problem with valves. Leaks generally take place because of the damage and wear of the valves. So, you can see leaks in the heater control valve application of your engine.
  • Electrical problems: Some of the heater control valve applications are managed by electrical systems. And if there is a problem with the electrical system of your car or the electrical connections of the heater control valve, the valve will not work properly.

Problematic actuator: Some heater control valve applications have actuator mechanisms that actuated with mechanic controllers or electrical controllers. And if there is a problem with the actıtor, controlling the valve will be impossible.

Stucks and clogs: And also clogged systems and the filth stuck on the valve mechanism can cause problems in general.

As you understand above, there can be different kinds of problems that take place for the heater control valve applications.

Symptoms of Faulty Heater Control Valve

There can be different symptoms of bad heater control valves. If you are aware of these general symptoms, knowing that you have a problem with your heater control valve will be much easier for you.

  • Heating problem: When you open the heat from the controller of your dashboard, the air is not heated. This can be because of that the valve is not opening.
  • Heat always comes: Also if the valve is stuck in one position because of a problem, you can not turn off the heated air. The air comes always heated.
  • Changing heat level: Also the heat level can change abruptly on its own. You can feel the loss of heat changes out of your control from your dashboard. The general cause of this problem is broken or worn-out valve claps.
  • Low coolant level: Also if you have a problem with the controller of the valve, the coolant can not come to the heater core.
  • Coolant leaks: If leaks are coming from the air conditioning system of your car, you may understand that there is a problem with your part.

General Repair Costs

Different kinds of parameters affect the repair costs of these valves. For example, the brand and model of the car and the type of problem that the valve have are the most important parameters.

But these are the general solutions that you can see for the different problems;

  • Debris removal: If there is a debris accumulation on the valve system, they will flush the cooling system to open the clogged sections. This may cost around $200.
  • Actuator repair or replacement: Also you may have problems with the actuator system of your car. The replacement cost of the actuator system of your car will be around $50-$350 according to the brand of your car.
  • Electrical repairs: Also the electromechanical system of the wiring and repairs can be the solution to your problem. These repairs may change around $100-$300 according to the type of problem.
  • Valve replacement: Also the solution to your problem can be the replacement of your valve system directly. This is the highest-price application that you can find as a solution. The replacement of the valve can cost around $150-$200 according to the type of your car.

Tips to Replacement of This Part

First of all, we need to state that the replacement of the heater control valve requires a professional approach. But we can give some tips that can be helpful for the people who will try to replace it. If youı are familiar with car mechanics and the general working principles of car engines, these tips will be very helpful for you.

  • Before starting, you need to find the place of the heater control valve. The place of it is generally in the engine compartment. You need to open the hood of your car and look at the firewall. It is generally connected with heater hoses.
  • You need to drain the coolant. And you need to be sure that the engine is cold before draining it.
  • Remove all the electrical connections and the hose connections from the valve. And remove the brackets that attached the vale to the engine compartment. And then, install the new valve to your engine.
  • And then refill the coolant to the air conditioning system.
  • Test the system if its works properly.

What Happens if You Bypass Heater Control Valve?

Bypassing this valve generally is not a good idea to make. Because the cabin of your car will not receive hot heat. And if you are living in climates where you do not have heat from the system, you can bypass it.

Maybe the valve system can be damaged and provides only hot air. And if you bypass it, you will get normal air or cold air from the system, if you do not pay extra money.

Can Heater Control Valve Cause Overheating?

Yes. If there are problems with the valve, it can not prevent the hot coolant from coming to the heater core. And this can be a problematic thing as overheating.


These are the general things that we can state about the heater control valve applications if you have additional comments and questions about them, leave them below.

They may seem very basic applications but in general, they are a very important part and they can cause major problems.

Related contents:

Capped Valve- A Useful Solution to Fluid Flow Systems

Car Seal Guide – How to Use? What Does it Mean?

Uğur Uygun

Hello everyone, I am Uğur. I am a mechanical engineer who has experience in different R&D departments of HVAC companies. With my best friend, I decided to build this website to share out knowledge and experience. And also, I am interested in automotive. So, I am writing about automotive and automotive-related articles here. Sharing my knowledge and experiences on these topics is a very big pleasure for me. I am willing to answer all of the questions people have about these topics.

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