Have you ever jumped in your car on a brisk morning, hoping for the car to heat up real quick and all it does is blow cold air? A failing heater is a frustrating issue that can leave you frozen in your tracks. Want help identifying the culprit and fixing the problem? Let’s look into some reasons why your car’s heater is blowing cold air.

Car Heater

(JoshuaJCreative / pixabay)

How Your Vehicle’s Heater Should Operate:

Typically, passenger vehicles have liquid-cooled engines. A mix of water and antifreeze flows through the engine, picking up excess heat generated by combustion and friction. After leaving the engine, the majority of the coolant travels to the radiator, where it cools before returning to the engine.

However, some of the coolant is diverted to the heating core, where it flows through a series of tubes. When you turn on your car’s heater, the fan kicks on, blowing air warmed by the warm coolant into the cabin of the vehicle.

This lengthy process is why it takes a while to warm up and why the engine needs to run for a bit before there is enough heat to warm your frigid hands. Various issues, however, can cause the vehicle’s heater to blow cold air, and the following are some causes to look into.

1. You Have a Broken Thermostat: The thermostat is a valve which opens and closes relative to the coolant’s temperature. These valves stay closed until the engine warms to a certain temperature. If the valves do not open when the temperature is reached, the coolant will not disperse correctly. This not only causes the heater to blow cold air, but as a result, could also act as a cause for the engine to overheat.

Conversely, if the thermostat is stuck open and refuses to close, the engine will take much longer to heat up. If the heater blows lukewarm air as opposed to freezing cold air, there is a good chance that an open thermostat could be the cause.

The thermostat gauge should be able to communicate to the heater core that the engine is warm, which should kick start the process of warming up the rest of the vehicle. If not, this might mean that the thermostat is broken, that the coolant won’t move over to the heater core, and that the rest of the vehicle will stay cold. Broken thermostats are a pretty simple and affordable fix, so contact your local Sugar House auto repair shop so you can get a functioning thermostat installed and get your heater operating again.

2. Your Coolant Level is Low: Coolant is used to cool the engine down, which is especially important during the hotter months. However, during the colder months, the coolant is responsible for carrying warmth generated by the engine to the heater core to create warm air. Low coolant means that there is less going to the heater core to help make warm air. Adding more coolant may solve the problem and help your car heat up faster in the winter.

3. There is Air in the Cooling System: The heater core usually sits at the high point of a cooling system. Sometimes air moving through will become trapped. These air bubbles can make it difficult for coolant to flow through the system. Should that be the problem, it can be fixed by flushing out the air bubbles.

4. The Heater Core is Clogged: The heater core usually sits directly at the back of the dashboard and is mainly responsible for defrosting and heating the vehicle. Heater cores are a cooling apparatus made up of tubing that moves the hot coolant from the engine in and out to help diffuse the heat brought by the coolant.

Some signs that you may look for to find out whether there is an issue with the heater core are:

  • Your vehicle is using up more coolant than usual
  • The engine keeps overheating
  • There is fog inside the vehicle
  • There is a sweet, fruity odor inside the vehicle

If you notice any of these signs, the heater core may be clogged. There are lots of ways this could happen. There could be junk or corrosion blocking up the heater core’s internal tubes, which could be fixed with some flushing. Or the heater core fins may also be blocked with debris, including pine needles, lint, or other tiny particles that find their way into the heater core. To fix this, simply open or take out the heater box and polish the fins on the heater core.

5. There is a Coolant Leak: Another common issue might be a water leak. Since there are lots of places where water leaks may show up, be sure to check the radiator, water pump, and hoses thoroughly for any leaking. These will prevent your vehicle’s car heater from working properly.

A good heating system makes those cold days and icy mornings more bearable. If you notice any of the above issues, look up your local Utah auto shop today to get your heating system fixed. With trusted auto repair shops from Park City to West Jordan, Burt Brothers ASE certified technicians are ready to help resolve your vehicle’s heating problems today.


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