Why is My Heater Blowing Cold Air in My Car?

Why is My Heater Blowing Cold Air in My Car?

7th Mar 2016

If your car heater isn’t working, a winter commute becomes miserable. If your heater is on but it’s not blowing hot air, it's time to address this issue.

How Heaters for Cars 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 heating, ventilation, and air conditioning (HVAC) system through the heater core. The hot coolant moves through the radiator. A fan behind the radiator blows cooler air from outside 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. It also allows excess heat from the engine to be used for other purposes.

“Why is My Heater Not Working Properly?”

That’s a good question, and there are a large number of possible ways to answer it. Here are some of the most common issues that can lead to heater problems in your vehicle:

1. A Radiator Leak

This is one of the most common and easily spotted reasons. Because coolant is pumped through the radiator, a leak causes radiator fluid to drip onto the heater core. If you smell a sweet scent coming from the vents, you probably have a radiator leak. These leaks also leave steam on the windows. A broken or cracked heater core will either need to be fixed or completely replaced. Don’t run the heater until you get this taken care of.

2. Low Engine Coolant Levels

This can lead to your car’s heater not working. 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 can be solved by replacing the engine coolant. On a similar note, the inside of your heater core might start to build up with old, sticky film and material. This also causes heat problems. Occasionally the coolant will need to be flushed and replaced.

3. Stuck Engine Thermostat

In this situation, there is no problem with the heater core or the coolant. The problem is 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 stuck thermostat doesn’t let coolant pass through the engine and heat up. This result is a heater that isn’t functioning. If your car is taking more than five minutes to produce heat, your thermostat is probably stuck. You can remove it and replace it, or have a mechanic do it for you.

4. Broken Cooling System Fan

Not all heating issues are related to the coolant or heater core. A broken fan leads to you having no heat inside your car. If there is no air blowing through the vents, or if the airflow is weak, the fan is broken. This is a part that can be replaced fairly quickly by most do-it-yourselfers and qualified mechanics.

5. Stuck Button or Electrical Signals

Most modern cars use electrical thermostats and buttons to operate the heat. In some cases, buttons get stuck. Electrical signals can get broken due to shorts or bad wiring. If all other problems are not the root cause of the problem, the electrical system might be the issue. You can conduct a car inspection or have a mechanic do it.

Maintaining Your Vehicle’s Heating System

The heater in your car is key to your engine’s health. The coolant keeps the engine from overheating, warping, and dying. Taking care of your car’s heater is an investment in its long-term health. The best way to keep your heat going is to take early and regular action when problems arise.

Most car heater problems relate to the coolant. Making sure this coolant is topped off is the best way to maintain the heater. You should also make sure to have the entire coolant system flushed and refilled on a regular basis. Keep in mind that newer vehicles can go 60,000 to 100,000 miles before needing a complete coolant change.

JB Tools Can Help With Your Car Heater Maintenance

We have the biggest selection of tools at the best prices. Whatever needs to be fixed, we have the tools you need to do it. For example, we carry a huge variety of hand tools as well as a coolant exchange system and radiator stop leak product. Our selection plus our free shipping on most orders makes us the best place to buy tools.

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