Why Is My Car Heater Blowing Cold Air?


Interior of Vehicle | Lou's Car Care Center, Inc.


It’s a crisp winter morning and there’s frost on your car. You climb inside, start the car, and let it warm up. But after a few minutes the heater is still  blowing cold air! As frustrating as this may be, this issue is not uncommon. Read on to learn more about the reasons why your car heater could be blowing cold air.

How Does My Heater Work?

Believe it or not, your heater is part of the cooling system. The cooling system protects your vehicle from overheating. Most cars and trucks have water-cooled engines. Water and a coolant mixture are circulated through a radiator. This helps to transfer heat away from the engine. However, before the hot coolant reaches your radiator, it goes through the heater core. Your car’s heater core is a smaller version of your radiator and is located behind the dashboard. When you turn the heat on, a fan blows air through the heater core warmed by the engine coolant. And into the cabin of your vehicle.

Heat Vent and Heater Control | Lou's Car Care Center, Inc.


Why Is My Car Heater Blowing Cold Air?

Here are a few possible reasons why your vehicle’s heater is blowing cold air:

  • Low on Coolant / Antifreeze

When you want warm air in your vehicle, the coolant / antifreeze is sent to the heater core from the engine. This hot air is then blown into the cabin. As your engine warms up, the air should become warm as well. If the air from the vents is still cold after your engine has reached the optimal temperature, you may want to check your coolant level. Low coolant/antifreeze levels will not allow the heater core to send warm air through the vents.

  • Broken Heater Core

A broken heater core is a common reason why your heater could be blowing cold air. A clog or block within it will cause the coolant to not travel properly through the heater core. If you notice a sweet smell coming from your vents or the inside of your vehicle gets foggy, these may be indications that your heater core is bad. A broken heater core should be addressed soon. It could cause damage to your engine from overheating.

Heater Core | Lou's Car Care Center, Inc.

  • Bad Thermostat

The temperature gauge on your dashboard is a great place to look if your heater is blowing cold air. After starting your car and letting the engine warm up, you’ll notice the temperature gauge needle move from the  “C” toward the “H”. If you have a bad thermostat, the needle will likely stay on the “C”. If the thermostat cannot communicate to your vehicle that the engine is warm, the heating system will not engage.

Some vehicles do not have temperature gauges, but rather dashboard lights to indicate the temperature. A blue thermostat light will show up on your dashboard when you first start your car. Once the engine has reached it’s optimal running temperature, the light will turn off. If the blue light remains on the dash even after you’ve been driving, it is time to have an auto technician look into a possible thermostat problem.

Electronic Temperature Gauge | Lou's Car Care Center, Inc.

  • Broken Heater Controls

The dashboard buttons or knobs that control the heating system can get stuck or stop working. A disruption in communication between these buttons and the heating system can cause the heater to blow cold air.

Vehicle Temperature Control Knobs | Lou's Car Care Center, Inc.

  • Water Leak

Your vehicle uses many fluids so leaks can occur is several places. It is possible that a hose, the water pump or your radiator could have a leak if you are unable to get hot air from your heater.

Vehicle Vent | Lou's Car Care Center, Inc.


Is your heater blowing cold air? We can help! Our experienced auto technicians can restore the heat in your cabin and have you and your loved ones back on the road safely. Lou’s Car Care is the right choice for all of your auto repair and maintenance needs. Proudly serving the Baldwinsville, NY, and surrounding communities since 1976. Call us or schedule your next appointment online today!



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