car heater cabin

No Heat in the Cabin – Common Reasons & Fixes

In Coolant by Magnus Sellén1 Comment

car heater cabin

Driving during the winter season can be very unpleasant, especially if you do not have a working heater in your car.

Yes, you can wear warm clothes, but it is not a good idea to go out looking like a shoplifter having a field day, and it is not very comfortable either.

There is simply nothing like a nice heater to keep you warm and stuffy in your car.

Problems with the heating system are quite common. In this article, we discuss the most common reasons why you don’t have heat in your cabin.

Reasons why there is no heat in the cabin of your car

The heating system of your car is quite complex and there are many parts that could have failed, leading to a lack of heat coming from the system. However, on newer cars, the system is advanced and has a control unit that controls all the flaps and engines. For this reason, you can often use an OBD2 scanner to easily locate defective parts.

Here are some of the reasons why your car cabin has no heat.

1. Not Enough Coolant Water in the Car

The most common problem when you have no heat in the cabin is actually a low coolant level. Open your bonnet and check the coolant level (when the engine is cold).

The heater in your car basically works by absorbing heat from the coolant flowing through your engine. The engine has a fairly high operating temperature (195 – 220 Fahrenheit), which warms the coolant quickly. The coolant has a long cycle in which it flows from the radiator to the engine and back into the radiator, where it ends up touching the heater. So if you feel that your heater is not working, even if your engine has warmed up well, it’s time to check your coolant level.

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The coolant is usually kept in a small container slightly separate from the radiator. If this is not the case, you can add antifreeze or even some water to bring the coolant level back up to the maximum. If the problem persists, there is something else that is worrying your heating system.

2. Malfunctioning Thermostat

The thermostat in a car regulates and measures the temperature of the engine. It determines how much water needs to be released to keep the engine at the optimum temperature. Fortunately, it is very easy to check a defective thermostat.

You need to start your car cold and keep your eyes fixed on the temperature gauge. If the temperature indicator rises after a few minutes, this means that your thermostat is working, but if it does not rise at all, there is a malfunction. If the temperature rises to half, you should open the heater to see if it works. If it still does not work, your thermostat is not the cause of the problem.

3. Air Lock in the Coolant Pipes

So, the thermostat is working perfectly and there is sufficient water/coolant in the radiator. The other thing that can go wrong is an airlock in the heating system. Sometimes dirt or air can block the heating and cooling system, making it difficult for the radiator to work. If you have some experience in removing air blockages, removing this air blockage should be just as easy. The radiator has a vent screw, or more simply, an air outlet that allows you to remove the air from the pipes.

All you have to do is locate the air vent screw in the radiator and start the car. Once the engine is running and the radiator fan starts, unscrew the bleed screw, and after a while, you will hear a sharp hissing sound from the outlet. That’s the airlock being removed. If any of these instructions sound too complicated, you can always get the help of a friend, or better yet, a mechanic who will do the work for you.

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4. Broken Heater Controls

car heat cabin

The heating is operated via a series of controls that are available inside the car. You can change the temperature and other settings while sitting in your car. Therefore, if nothing else works, it is possible that only the controls are stuck or broken.

These controls are made of cheap materials like plastic, which makes them very vulnerable to damage. There are many YouTube videos on the internet that show you how to repair the heating controls, but if you are not a DIY enthusiast, you can invest in some new controls. They are quite cheap, so you won’t feel the dent in your pocket.

In some cases, you will need to replace the entire heating control unit.

5. Broken Heater Flaps/motors

Under your dashboard are flaps that regulate either the airflow or the coolant flow through your heating matrix. If one of these flaps/electric motors is defective, there is a great risk that your heater will not function as suggested.

If you have a newer car with electric motors on the flaps – you will most likely get an error code on them when you scan the system with a diagnostic computer.

You can also locate the flaps and try to see if they move when you change the heater control.

6. Clogged Heater Matrix

If nothing seems to be working, it is possible that your heating matrix has gone bad, which means you are about to take a trip to the mechanic. The heating matrix is the heart of the heating system, so it is obvious that if the heating matrix fails, your entire heating system will fail.

The heating matrix is an expensive component, and replacing it is often a challenging task as it is often installed deep under the dashboard. The mechanic would charge you about $600 to $1000 depending on the make and model of your car. Of this total cost, the radiator itself is charged at $100 to $250.

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The real culprit is the cost of labor, as you may have noticed, because the cost of labor for such work is usually high.

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.

1 thought on “ No Heat in the Cabin – Common Reasons & Fixes ”

  1. Correction. Excellent diagnosis but it lacked images for quick understanding.


  2. Due to a very high demand and high ammount of comments, you have to wait for some time for your car questions to get answered. If you want to get fast answers from a certified master technician you can ask your questions here:
    Ask A Mechanic

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