Car heater blowing cold air

Car heater blowing cold air

In Diagnostics by Steves Auto Repair and Tire

If you’re like me, you have or are getting ready to turn the heat on during your morning commute.

When you do it the first couple of times this season, you may notice a couple of problems.

A burning smell is one of them. This can happen if dirt kicks up in an area that hasn’t been used in a while. But if the issue persists, you should have it checked out at a repair shop near you.

The car heater blowing cold air is another common problem, which can stem from several underlying issues. These reasons include:

  • Low on coolant
  • Heater core problems
  • Thermostat not working
  • Blocked or broken heater control  

We will provide a deeper explanation about each possible cause below.

Low on coolant

A car heater not blowing hot air can occur when a vehicle’s coolant level is low. Coolant helps ensure that the engine temperature doesn’t get too high and prevents issues, like your car overheating. The warm air you feel when you turn on your heat is generated by hot coolant from the engine. If the right amount of coolant isn’t in the system – typically the result of a coolant leak – the heater won’t function correctly.

Heater core problems

We mentioned earlier that hot coolant is needed to warm up a vehicle. The heater core is also a necessary part of this process. A car heater not working could be caused by a bad heater core or if the heater core is leaking. Bad heater core symptoms include the vents blowing cold air, and fog on the windows or in the front seats. Debris called “scale” could also be blocking this component, preventing coolant from making it into the heater core.

Thermostat not working

If a car heater isn’t doing its job, there may be a problem with the thermostat, which opens and closes based on the coolant’s temperature. A bad thermostat may cause the engine to become too hot or too cold and lead to the car heater blowing cold air.

Blocked or broken heater control

Another possible issue is a blocked or broken heater control. For a heater control problem, it can be a few things. With today’s vehicles having a lot of electronics in them, there are “mode door actuators,” which are little electric motors that move a little door back and forth. That allows the air to go through the heater core, or not, and helps adjust the temperature. You can also have a blend door sensor made out of plastic that can break and won’t move, only allowing you to feel cold air. You can also have problems with heater control cables on some of the older vehicles. Blockages may occur in the air distribution box – where the heater core is located – as well. Mouse nests, papers and other items can prevent air from making it to the heater core.

The type of car heater repair needed varies for each problem. Our technicians are able to perform diagnostic testing and replace the parts needed to address it.

Sometimes, if the heater core needs to be replaced the whole dash of the vehicle must be removed. This can take a little bit of time, so if you need a new heater core plan to be without your car for one to three days.

Steve’s Auto Repair & Tire is an authorized Goodyear tire dealer located in Woodbridge, Virginia. Automotive repair services are performed on all makes and models, including BMW and Mercedes. Services include oil changes, brakes, alignments, inspections, and computer engine diagnostics.