The method used to warm a car’s cabin isn’t a whole lot different from the one used to keep its engine cool. In fact, it’s all hooked together and runs on the same circuit. Coolant circulates through the engine and absorbs engine heat, which is exchanged with the outside air by way of the radiator. A much smaller radiator called the heater core uses the same hot coolant to keep the cabin toasty. In general, there are two things that can go wrong with this setup.
The first item to check is the engine temperature. To help cold engines warm up fast, the flow of coolant is restricted by way of the thermostat, a thermal valve that opens when it’s hot and closes when it’s cold. When the thermostat wears out, it remains stuck open or shut, which leads to either overheating or cool operation. A worn-out thermostat might be preventing the coolant from getting warm enough to heat the cabin.
If the thermostat is fine, the flow of coolant in the heater core may be restricted by built-up goop. Sediment and grime can accumulate between coolant changes and collect in the heater core. A coolant flush may be in order.
Before you get caught out in the cold, bring your vehicle in for a heating system check and find out if it’s due for a cooling system flush. We’re offering a Winterization Special now — for only $119, you can get an oil change, tire rotation and coolant flush and have your front washer blades replaced and your starting and charging system inspected. Take advantage of this $60 savings now and stay in the hot seat!
Adapted from the article “What’s Wrong with My Car’s Heater” by Ben Wojdyla published in Popular Mechanics.