Are Your Car’s Heater Vents Blowing Cold Air?

Freezing winter temperatures are when you least want your vehicle’s heater to go out. And so, by Murphy’s Law, that is when it will happen. Not only will this make your morning drive much less fun; if your heater isn’t getting warm sufficiently to defrost your windshield, your car can be dangerous to drive.

Christian Brothers Automotive will walk you through the most likely troubleshooting steps to get the hot air flowing before you turn into a popsicle behind the wheel.

Your car heater operates by taking heat from the engine by way of the coolant/antifreeze that circulates through it. The coolant then collects the heat in the radiator, where it is blown into the outside world. Along the way, the coolant goes through the heater core, where some of the heat can be sent through the dashboard instead of outside the car.

The first thing to consider, therefore, is the level of antifreeze in your car. If the level is low – because of a leak or something else – then not enough heat will be transferred through the engine into the heater core. This can cause not only an inoperative heater, but also an overheated engine.

If you have enough antifreeze, the next step is to check the temperature gauge. Does it say the engine is too hot? Does it act erratically as you drive, or when you turn on the heater? Your engine‘s thermostat regulates the coolant movement. When it is at the end of its life, it sticks either open or shut. Sticking closed can make the engine overheat. Sticking open allows coolant into the engine before it gets hot, which means the vehicle – engine and cabin alike – takes longer to get up to the right temperature. In many cars, the thermostat is an easy fix, but in a few, it’s more difficult to access. In any case, your friendly Christian Brothers mechanic can fix it for you.

If your blower fan isn’t turning on, then no matter how hot the heater core becomes, it won’t be distributed through to the driver and passengers. The malfunction could be with the fan itself, a sensor, or the electrical connection. If your vents don’t even blow cold air, this is probably what’s wrong.

It’s also conceivable that the heater core itself is congested with particles and needs to be flushed. When this is the case, we access its hoses and pump air through it to ensure efficient flow. We then flush the system, taking care not to slop coolant everywhere. It’s a messy job, but someone has to do it – and we’re available so that you don’t have to.