Reasons Why Your Gas Furnace May Stop Blowing Warm Air

Posted on: 25 September 2020

During the winter months, you most likely rely on your home's furnace to keep the inside of your house warm and comfortable when it is frigidly cold outside. Thus, if your furnace stops operating properly, it is natural to feel alarmed. The good news is that if your furnace stops blowing warm air, it doesn't mean that the furnace needs to be replaced — most issues can be repaired by an experienced HVAC technician. Some common reasons why your furnace may stop producing warm air include the following.

Clogged Burner

The burner in a furnace plays an important role in creating hot air. Fuel and air come together in the burner, causing a combustion that produces heat. However, if your furnace has not been properly maintained or is quite old, it is possible for debris to build up on the burner, causing a clog. When this happens, fuel can't flow into the burner, so warm air can't be made. In this type of situation, the fan in the furnace may still run, so it will sound like the furnace is operating, but no warm air will blow out. Having the burner thoroughly cleaned and ensuring that all debris is removed will typically resolve the issue.

Problems with the Gas Valve

When you have a gas furnace, the system needs a continual flow of natural gas in order to operate properly. However, the gas valve in your furnace can develop problems that prevent the natural gas from flowing. In some cases, dirt and debris can block the gas valve, which results in no warm air being produced. It is also possible for a gas valve to break or wear out; when this happens, you will need to have the faulty gas valve replaced with a new one.

Faulty High Limit Switch

Furnaces have a component built in to help prevent the unit from overheating — this component is called the high limit switch. When the high limit switch wears out or becomes faulty, it will no longer send the right information to the unit, and the furnace will assume that it is overheating. When this happens, the furnace fan will turn on and the furnace will stop making warm air. Your furnace will not run reliably and consistently produce warm air if there is anything wrong with the high limit switch. An HVAC technician can remove the bad high limit switch and install a new one to solve the issue.

For more information, contact a local furnace repair service.


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