car heater cabin

No Heat in the Cabin – Common Reasons & Fixes

In Coolant by Magnus Sellén1 Comment

car heater cabinGoing for a drive in the winter season can be very uncomfortable especially if you do not have a working heater in your car.

Yes, you can wear warm clothing but it is not a great idea to walk out of your house looking like a shoplifter having a field day neither is it comfortable.

You just can’t beat a nice heater keeping you warm and stuffy inside your car.

Problems with the heating system are pretty common. In this article, we will discuss the most common reasons why you do not have any heat in your cabin.

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

The heater system of your car is pretty complex and there are a lot of parts that could fail when you do not get any heat from the system. However, the system on newer cars are advanced and got a control unit that is controlling all the flaps and motors. Because of this, you can often use an OBD2 scanner to locate broken parts easily.

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 do not have any heat in the cabin is actually a low level of coolant. Open your hood and check the coolant level (When the engine is cold).

The heater in your car basically works by absorbing heat from the coolant that runs through your engine. The engine has a pretty high operating temperature (195 – 220 Fahrenheit) which warms the coolant quickly. The coolant has a long cycle where it goes from the radiator to the engine and back into the radiator where at the end it touches the heater. So, if you feel that your heater is not working even after your engine has heated up fine, it is time to check your coolant levels.

The coolant is usually stored in a small container a bit separate from the radiator. Check to see if that container has adequate levels of coolant and if not you can proceed to add anti-freeze coolant or even some water to bring the levels back to maximum. If the problem persists then there is something else troubling your heater system.

2. Malfunctioning Thermostat

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

You need to start your car cold and keep your eyes fixated on the temperature gauge. If after a few minutes the temperature gauge rises, it means your thermostat is working however if it doesn’t rise at all it means there is a malfunction. When it does rise halfway you should open up the heater to see if it is working. If it does not work still then your thermostat is not the root cause of the problem.

3. Air Lock in the Coolant Pipes

So, the thermostat is working fine 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 hard for the heater to work. If you have some experience clearing air blocks then clearing this one should be just as easy. The radiator has a bleed screw or in simpler words an air leaking outlet that allows you to clear the air from the pipes.

All you have to do is locate the bleed screw in the radiator and start the car. Once the engine starts running and the radiator fan starts up unscrew the bleed port and after some time you will hear a sharp hiss coming from the outlet. That is the airlock being removed. If any of these instructions sound too complicated you can always acquire the help of a friend or better yet you can consult a mechanic to do the job for you.

4. Broken Heater Controls

car heat cabinThe heater is operated through a set of controls provided to you inside the car. You can toggle the temperature and other settings while sitting inside your car. Therefore, it is possible that when nothing else is working then it is just the controls that are stuck or broken.

These controls are built from cheap materials like plastic which makes them highly susceptible to damage. There are many YouTube videos on the internet that will show you how to fix the heater controls but if you are not a DIY person then you can invest in some new controls. They are pretty cheap so you won’t feel the dent in your pocket.

In some cases, you have to replace the whole heater control unit.

5. Broken Heater Flaps/motors

Under your dashboard, there are flaps that are regulating either the airflow or the coolant flow through your heater matrix. If any of these flaps/electric motors are broken, there is a big risk that your heat won’t work as suggested.

If you have a newer car with electric motors to the flaps – you will most likely get a trouble code on them when you are searching through the system with a diagnostic computer.

You can also locate the flaps and try to see if you can see them moving when you are changing the heater control.

6. Clogged Heater Matrix

If nothing seems to work then it is possible that your heater matrix has gone bad and that means you are looking at a trip to the mechanic. The heater matrix is the core of the heating system so it is obvious that if the heater matrix goes bad your entire heating system fails.

The heater matrix is an expensive component and the replacement is often an advanced task because it’s often fitted deep under your dashboard. The mechanic would charge you approximately $600 – $1000 depending on the make and model of your vehicle. From that total cost, the heater core itself is priced at $100 – $250.

The real culprit is the labor cost and as you might have noticed for such a job the labor cost tends to be 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.

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

    Thanks.

  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:
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