Your Hyundai uses engine coolant to create the warm air it then pumps into the cabin to keep you warm in the winter. The hot coolant flows through the heater core, which, like a mini radiator, then blows warm air into the cabin thanks to a blower fan in the heater core.

If you have little or leaking coolant, then there isn’t enough hot fluid to properly circulate and warm up the heater core. Leaks can be found in the hoses or the water pump, and can cause coolant to drop below a safe level. Check your coolant level and look for signs of wet spots or white crust around hoses for a leak, or take your Hyundai vehicle to a team of trained technicians to do so for you.

The heater core usually sits at the high point of a cooling system. Sometimes air moving through will become trapped, which makes it tricky for coolant to flow through the system. Flushing out the air bubbles will solve this problem, but should be done by a team of trained technicians.

The heater core, over time, can get clogged, especially if you don’t change your coolant regularly. If you notice your windows fogging up or that it takes longer to warm up your vehicle, this could be the reason. Trained technicians will flush or replace your heater core to solve this issue for you.

The thermostat is what makes coolant circulate through the engine. If it gets stuck in the open position, the engine will stay cool and never generate enough heat to then pass on to the cabin. On the other hand, if it gets stuck in the closed position, the engine can overheat, which can lead to serious damage. If you’re driving around for hours and your Hyundai isn’t warming up though, the thermostat being stuck in the open position might be the culprit.

Remember how we mentioned earlier that the heater core has a blower fan that gets the warm air into your cabin? If this fan is broken, it can’t blow air into the cabin at all, be it warm or cool, and your Hyundai vehicle will stay cold due to the outside temperature.