Winter mornings can be brutal without a working car heater. You crank the dial to full blast, and all you get is cold air. What’s going on? As someone who’s spent years listening to drivers vent (pun intended), I’ve seen it all. Here are the most common reasons your car’s heat might stop working. I’ll start with a couple of lesser-known problems.

The engine isn’t given enough time to warm up

This could happen if you only take short trips or if it’s bitterly cold outside. Try driving your car a bit longer to see if the heat kicks in. If not, it could be one of the following components.

A bad blend door actuator

Modern cars rely on blend doors to control airflow and temperature inside the cabin. These little doors are powered by actuators, and when one fails, you might get no heat—or heat only on one side. If you hear clicking behind the dash or can’t control the temperature, the actuator is likely to blame.

Low coolant level

Your car’s heater relies on engine coolant to generate warmth. If your coolant is low, there’s less to circulate through the heater core. This is an easy one to check—just pop the hood and look at the coolant reservoir. Be sure to top it off with the right mix if it’s low. But keep in mind: low coolant typically points to a leak somewhere in the system.

Air trapped in the cooling system

On a related note, air pockets in the cooling system can disrupt the flow of coolant to the heater core. This usually happens after a coolant flush or repair. Bleeding the system to remove the air can restore proper flow. If your heater started acting up right after a service, this might be your culprit.

A faulty thermostat

The thermostat is the traffic cop of your engine’s cooling system. When it goes bad, it can’t regulate the flow of coolant. That means your engine might not get hot enough for the heater to work. Symptoms often include a temperature gauge that stays stubbornly low. Fixing this is usually straightforward and not too expensive, so don’t sweat it.

A bad heater core

Think of the heater core as a mini radiator tucked behind your dashboard. It transfers engine heat to the air blowing into your cabin. If it’s clogged, leaking, or just plain worn out, your heater won’t do its job. A sweet, syrupy smell in the cabin or foggy windows could be warning signs. Heater core repairs are tricky – after all, they often require removing the dash from the vehicle – and can cost a pretty penny, but it’s not the end of the world.

Blower motor problems

Your blower motor pushes warm air through your vents. If it stops working, you won’t feel any air movement, hot or cold. Sometimes, the issue is a simple blown fuse or a bad relay. Other times, the motor itself needs replacing.

When your car’s heat stops working, don’t panic. These problems are often super common for mechanics and very much fixable. Just pinpoint the symptoms and get your car checked out. These issues typically still mean you’ll soon be warm and toasty again.