Heater and air conditioning controls on a car.

Common car heater problems

In Automotive Diagnostics by HomeTowne Auto Repair & Tire

Your car heater can be just what you need on chilly winter, fall or spring days. However, there may come a time where you flip it on and feel cold air blowing through the vents – even after the vehicle has been running for a while. 

What can cause this unpleasant occurrence? Well, a car heater blowing cold air can be the result of a few problems. It could indicate:

  • More coolant is needed
  • There is a problem with the heater core
  • The thermostat isn’t functioning correctly
  • The heater control has become blocked or broken

Below is more information about these different issues.

Car heater problems? Here’s what it could be.

It needs more coolant: Hot air generates from the heater core. Coolant, which runs through the engine and heater core, becomes hot. Coolant has to go somewhere, so if you need to add coolant, it’s likely that there’s a leak. Coolant leaks, which are also known as “water leaks”, can develop anywhere – the heater core, radiator, heater hoses, thermostat, and other areas.

Problems with the heater core: The heater core can become blocked by scale, which is debris created by a chemical reaction. If the heater core is blocked, coolant isn’t able to enter it and send cold or hot air through the vents. 

The thermostat is malfunctioning: The thermostat expands and contracts, depending on the coolant’s temperature. If it’s stuck open, too much coolant is flowing, causing the engine temperature to stay too low. This can cause cold air to come through the vents. If the thermostat is stuck closed, the engine temperature becomes too hot.

Heater control is broken or blocked: The blendor actuator, or “blendor switch” – the knob on your dashboard – tells the actuator how much to open the door. This determines how hot or cold the air that enters your vehicle is. If it breaks or gets clogged, air – or the type of air you want – won’t flow through. Blockages may be caused by papers, mouse nests or other objects. If the car heating problem is occurring on an older car, there might be something wrong with the cables for the heater control.

What do I do if my heater is blowing cold air?

When you realize you have a car heater problem, take a few minutes to look at the heating system. You or one of your passengers could have accidentally pressed the wrong button or adjusted the settings.

Once you have confirmed that everything appears to be set correctly, contact a nearby car repair shop. They may be able to help you troubleshoot it. They can also have one of their mechanics take a look if it seems to be a deeper issue, or diagnostic testing is needed to resolve the problem.

HomeTowne Auto Repair offers car heater repair services. Our automotive technicians can help you figure out where the trouble lies and restore that precious heat to your vehicle.

HomeTowne Auto Repair & Tire is an authorized Michelin and BFGoodrich tire dealer located in Woodbridge, Virginia. Automotive repair services are performed on all makes and models, including oil changes, brakes, alignments, inspections, and computer engine diagnostics.