When it's cold outside, you expect your furnace to kick on and keep you nice and warm indoors. When your furnace doesn't blow out air at all, it's definitely a cause for alarm. Rule out simple things first like the thermostat setting and the electrical panel for a tripped circuit. If neither of those steps helps, you'll probably want to call an HVAC technician to make repairs to your furnace so your home can warm up again. Here are a few things that might be wrong with your furnace when it stops blowing air.

The Limit Switch Is Triggered Or Bad

The limit switch detects heat in your furnace and turns it off when the setpoint is reached. If the switch is bad, it may keep your furnace turned off even though it's cold in your house. Sometimes, the switch turns your furnace off when it overheats due to a malfunction. One common reason for this is dust buildup. If your furnace filter is so dusty that it's caked solid and very little air can get sucked into the furnace, then your furnace can overheat and the limit switch will shut it down for safety reasons.

Check your filter to see if it is in desperate need of replacement or cleaning. If that doesn't help, the switch could need to be replaced. The HVAC technician will check it along with other possible causes to find out why your furnace won't work.

The Blower Is Bad

The blower is responsible for blowing air through your heating system and out of the ducts. The part consists of a motor and fan, and both of these need to be kept clean and in good repair to prevent problems with your furnace. Sometimes, your furnace will make clicking or squealing noises when the fan or motor is going bad. If you hear unusual noises coming from your furnace, you should have them investigated before your furnace stops working. When your furnace won't blow air, the blower is a suspect, but there's a way to tell if it's working. You can turn off the furnace at the thermostat and turn on the fan. If the fan kicks on, then you know it's okay. If it doesn't, then the technician has to determine if the problem is with the wiring or motor.

Determining why your furnace blower has stopped working starts by eliminating the most common reasons and working toward the less common and more expensive problems to repair. There are several causes for this annoying and inconvenient furnace malfunction, but a licensed HVAC technician can pinpoint the problem and make the necessary furnace repairs so you can warm up as soon as possible. Call a heating service for more information.