Identifying Why Your Car Heater Won't Work

Isaiah Chambers

After performing a repair or two, you may decide you're ready to tackle your next major repair. Then, your car heater stops working. As you try to decide whether you should try to repair your car heater yourself or take it to an auto body, you will need to find out why the heater is not working in the first place. Here are some possibilities:

Your Car Doesn't Have Enough Coolant

The coolant circulating through your car produces heat that is used to warm your car up. The heater is the last part of your car to receive the coolant, so if you don't have enough, your heater may stop working properly. Check the tank under the hood of your car to determine if you have enough.

The Thermostat Isn't Working

A malfunctioning thermostat causes a car heater to only work if the outside ambient temperature is very low. Thermostats in cars operate differently because they are designed to prevent the coolant from flowing until the coolant has reached a specific temperature. The thermostat will usually stay open once it has opened, unless the temperature is very cold. Then, it will close and prevent the heater from working.

Your thermostat might also become stuck, preventing it from opening regardless of the temperature. Run your car and keep the heater on while waiting for 10 minutes. Then, look at the thermostat dial to determine if it is still on cold. If so, the thermostat is stuck and may need to be replaced.

The Fan Isn't Working

When you are driving over 40 miles per hour, you may feel a small trickle of heat. This indicates that the heater is working, but that the fan is not spinning properly and delivering the heated air into the car interior. Try different fan speeds and see if the amount of heat entering the car interior changes. If not, there might be something wrong with the fan.

If you need professional help to inspect your vehicle, visit an auto body shop like Collision One.

There is an Air Pocket

Air pockets prevent coolant from flowing through the heater core. Find the heater hoses and feel them while the heater and engine are running. If they are hot, there might be an air pocket preventing the coolant from flowing properly.

A defective heater could indicate a more serious problem that will cause your engine to overheat. Therefore, if you can't identify the cause of the defective heater, you should take your car to an auto body repair shop.