Why Does My Car Heater Only Work Sometimes

Your vehicle's heater works simultaneously with your cooling system to deliver both heat and AC to your vents. Many problems with inconsistent temperatures usually stem from coolant fluid-related issues. If your heat isn't blowing warm air, only when your car is stopped or parked, it may be due to the following matters: 

Low Coolant Levels

Coolant is like the superfluid of all fluids; it regulates engine temperature and airflow coming into the passenger cabin. The air starts in the engine compartment, where heat accumulates. The coolant helps draw this generated heat by moving it to your radiator.

If the coolant is low and you have your heater on, you may catch that your car heater only works when you're driving, not idling. Your first instinct should be to check the coolant. Irregular car care and leaks are two of the most common reasons behind low coolant. Whatever the cause, it's best to take your automobile to the experts at County Line Auto Service for an inspection and repair.

Malfunctioning Thermostat 

The thermostat monitors engine temperature and controls coolant flow according to its readings. Debris and corrosion can often clog the thermostat and stop it from opening and closing correctly. If the thermostat stays open, you may experience a low engine temperature and little to no heat.

Jammed Heater Core

A blocked heater core is a more rare problem, but it is not impossible. As the name implies, the heater core warms up the air when needed, according to your preference. Your heater core may get blocked due to excess build-up. When you suspect you have a heater core problem on your hands, it's best to have your vehicle inspected by an experienced mechanic since this component can be challenging to get to.


Out of the three possible problems, low coolant levels are often the culprit in this case. If you ignore this issue, it can lead to poor engine performance and put it at risk of overheating. Don't freeze and wait too long - please have your car heater fixed at County Line Auto Service soon!

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