Car Heater Not Working? Troubleshooting and Repair Tips

Car Heater Not Working? Troubleshooting and Repair Tips

7th Mar 2016

With the car heater not working, any winter commute, can turn into an extremely miserable experience. If you’re turning your heater on and find that it is either not blowing heated air, or that the air is not reaching its full potential, it may be time to get your car heater inspected and fixed.

How Heaters Work

As your engine burns fuel, it produces hundreds of degrees of excess heat. Engine coolant is used to help keep the temperature from getting too hot. That coolant is pumped through the HVAC system (heating, ventilation, and air conditioning) of the car through the heater core. The hot coolant moves through the radiator. A fan behind the radiator will blow cooler air coming in from outside of the car over the radiator fins. This is how your car is capable of producing warm air that is not too hot and can be modulated to different temperatures. This also allows the excess heat from the car’s engine to be utilized for alternative purposes.

Why is My Heater Not Working Properly?

If you find your car heater not working when you step inside of your vehicle, there are a large number of possible issues. One of the easiest spotted reasons is a radiator leak. Because coolant is pumped through the radiator, a leak will cause radiator fluid to drip onto the heater core. If you smell a sweet scent coming from your vents, you have a radiator leak. The heat might be working, but you will notice the smell right away, especially while the heat is on. You should not run the heater while there is a radiator leak occurring. Similarly, alongside the sweet smell, if there is a leak in your heater core, it will leave steam on the windows inside the car. A broken or cracked heater core will either need to be mended by a mechanic or completely replaced.

Low coolant levels can also result in car heater not working. As stated, the coolant carries the heat from the engine to the radiator. Low fluid levels mean little to no heat is being transferred into the heater core. Thankfully, this is an issue than can be solved by replacing the engine coolant. On a similar note, the inside of your heater core may start to build up with old, sticky film and material. This can also cause heat problems. Occasionally the coolant will need to be flushed and replaced. A good mechanic can top off fluids, or flush and replace old fluids.

Occasionally, the only issue with the engine is a stuck thermostat. In this situation, there is no problem with the heater core of the coolant, but the mechanism that controls the flow of coolant through the engine. The engine thermostat has two states: open, when it is allowing coolant to flow through, and closed when it is not. A thermostat that is stuck closed will not allow coolant to pass through the engine and heat up. This results in a heater that appears to be nonfunctioning. If your car is taking more than five minutes to produce heat, this is a sign that your thermostat is stuck. You can remove the thermostat and replace it, or have a mechanic do the work for you.

There are some issues unrelated directly to the coolant or the heater core. For example, a broken fan that should be blowing air across the heater core will result in no heat inside your car. You can determine if this is the case if there is no air blowing through the vents, or if the air flow is extremely weak. This is a part that can be replaced fairly quickly by a mechanic.

Most modern cars utilize electrical thermostats and buttons to operate the heat in your car. In some cases, buttons can become stuck, or electrical signals can be broken due to shorts or bad wiring. These issues may be difficult to check yourself. If you have determined that all other problems are not the root cause of your car heater not working, the electrical system may be the root problem. Getting a mechanic to give your car an inspection is a good idea in this situation.

Maintaining the HVAC System

It’s important to remember that the heater in your car is tied intricately to your engine health. The coolant that is flowing through the heater core and providing heat to your car is an essential part of keeping your engine from overheating, warping and eventually dying. Taking care of your car’s heater is only one way of taking care of your car’s overall long term health. Ignoring either could easily mean trouble for you and your car. The best way to keep your heat going, especially in the winter, is to take early and regular action when any problems may arise.

Most car heater problems relate specifically to the coolant. The best way to maintain the heater in your car is by ensuring that coolant is topped off regularly. Secondly, make sure to have the entire coolant system flushed on a regular interval as well. Newer vehicles will likely be able to go 60,000 to 100,000 miles before needing a complete coolant change. However, getting professional assessments from a mechanic on a regular basis is the key to keeping your car’s heater core in good shape.

Download or share the following infographic to know when you need to know about car heater troubles!