Why Is My Car Heater Blowing Cold Air?

May 12, 2023
Hand reaching out to feel air from a car vent.

If you’ve sat in your car, turned on the heat for a few minutes, and feel cold air blowing instead of warm, you’re not alone. While frustrating, it’s a common issue during cold weather. Here are a few reasons why this could be happening and what you can do to fix.

Your coolant level is low

One of the main reasons your heater could be blowing cold air is your coolant is low. The coolant’s job is to keep the engine from overheating, and it’s the main source of heat that supports the heating system. The heater will blow cold air into your car if there isn’t enough coolant in the system. For many vehicles, checking for low coolant is pretty simple. Pop your hood and find the coolant reservoir and check to see if the coolant is at the right level. If it’s low, you can fill it to the prescribed level with the appropriate coolant fluid. A leak could also be the cause of the cold air, so make sure to check for leaks. If you’re not comfortable doing this yourself, you can go to an auto-parts store and ask for help. [1]

The car thermostat isn’t working

The job of a car’s thermostat is to regulate the flow of coolant through the engine. There are a few signs to look for when a car thermostat is failing. For example, the dashboard temperature gauge reads high, and the engine overheats, the temperature changes erratically, or the coolant leaks around the thermostat. Fortunately, car thermostats aren’t that expensive to replace. The average one costs only $8, so it makes more sense to replace your thermostat rather than fixing it. [2]

Heater core issues

There’s also a chance your heater isn’t working correctly due to issues with the heater core, or a small radiator that uses the hot coolant from the engine to warm the car’s cabin. [3] Either the coolant isn’t traveling through the heater core correctly, the blower motor air isn’t reaching the heater core or a clog is possibly blocking the heater core. It’s important to resolve this issue as soon as possible, as it can damage your engine and lead to it overheating.

If you notice a sweet-smelling odor, fog in the car’s cabin or your car is using up coolant too quickly, it could be a sign that you have heater core issues. Most of the time, this can be solved by flushing the heater core passage or by manually removing any debris that has clogged it. In rare cases, you might need to install a new heater core. [4]

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Water leaks

Another common problem with heaters is a water leak. Check your hoses, radiator and water pump for damage, as any of these have the potential to leak and cause your car heater to not work properly. If you notice a leak, contact your local auto repair shop to look at your heating system as soon as you see it. If you leave the issue without fixing it, it can cause major issues down the road. [5]

Jammed heating controls

The last potential cause for your heater blowing cool air instead of hot is that the heating controls might be jammed. If your car is somewhat older, it’s possible for your heating buttons and control to become clogged or broken. If all the other possible causes have been checked and aren’t a problem, then it might be time to replace some of the control buttons or your heater control valve. [4]

To make sure your car lasts as long as possible, it’s important that you keep up with its maintenance, including fixing any heater issues. Also, make sure that you invest in quality car insurance to ensure your vehicle and passengers are always protected.


[1] “Why is my car heater blowing cold air?” browndaubkia.com/why-is-my-car-heater-blowing-cold-air-easton-pa.html (accessed April 18, 2023).

[2] “What Should I Do If My Car Thermostat Starts to Fail?” Rick Muscoplat, familyhandyman.com/article/when-a-thermostat-fails/#how-to-test-a-car-thermostat (May 5, 2022).

[3] “Heater Core,” cars.com/auto-repair/glossary/heater-core (accessed April 21, 2023).

[4] “Car Heater Blowing Cold Air? Here’s Why!” nortexlubeandtune.com/blog/car-heater-blowing-cold-air-heres (Nov. 28, 2018).

[5] “Reasons Why Your Car Heater is Blowing Cool Air,” wkcdjrsedalia.com/research/reasons-car-heater-not-working.htm (accessed April 18, 2023).


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