What to Do When a Furnace Blower Won't Turn Off

A repair technician fixing a furnace.

Every forced hot air furnace has a furnace blower that makes air circulation possible for any house. A furnace that utilizes forced-hot-air is made of the plenum, the furnace blower, and the burner. In most cases, when used in a forced-hot-air system, oil, wood, or natural gas are used to fire up the burner. Air is then heated through the burner that was collected in the plenum. Then, hot air may be forced or be blown away from plenum all the way through the house using the furnace blower.

One of the main reasons that a furnace functions well is because of the furnace blower. The blower is an essential part of the heating system itself. If the furnace blower is not functioning well or is dirty, it will not function properly and that means there will be a waste of energy and money. There are many possible causes for an ill-functioning furnace.

Generally, if the furnace blower motors works continually, the limit switch or the roll-out switch is open or in bad condition. The furnace board sees that one of these switches is open that is why it causes the blower on to make an attempt to get the heat out of the combustion chamber zone. However, when the switch is in bad condition and will not close, the furnace board would continue to run the blower endlessly.

Understanding Furnace Blower

Understanding how a furnace works will help you to determine what the cause of the problem might be. If the furnace blower does not turn off, turns off too quickly or not quickly enough, as it blows cold air towards the end of the heating cycle, then the glitch is possibly a bad temperature control switch.

On the whole, the temperature control switches cannot be adjusted and are to be changed if they are defective. In case the furnace blower does not turn off and it is not bringing cold air, the furnace is still lit. If the furnace is still lit, do not turn off the blower.

Stop the Furnace

Lower the thermostat in order to stop the furnace. If that does not stop the furnace blower, switch off the thermostat. Initially, the burner will turn off and then the blower would turn off as well. In case the furnace turns off when the thermostat is turned to off, a probable reason is a thermostat that is not working properly. The solution to this problem is to replace the thermostat.

Consult a Professional

In case the thermostat is turned off but does not turn off the furnace blower, then find the breaker in the fuse box or the central on and off switch on the furnace and turn it off. After that, turn the gas off as well. The gas switch must be located in front of the furnace. If you do not properly turn it off, there may be problems ranging from a short in the wires to a bad gas valve. For that reason, it would be best to consult or let a professional troubleshoot and fix the problem.