Understanding Common Furnace Repairs: Fan Limit Switch
Heater repairs in Cincinnati made by the professionals at Pinnacle Air Solutions will ensure that an equipment problem is solved promptly and successfully. One serious problem that is usually overlooked until the problem progresses to the danger level is a failure of the high-limit switch, also known as a fan limit switch.
How A Furnace Works
A gas furnace ignites the burners before the blower motor begins to run. This delay allows the heat exchanger to warm up so that the cold air does not blow into the ducts. When the heat exchanger becomes warm enough to heat the air, the high-limit switch will then signal the blower motor to start running. This switch is also a very important safety mechanism, as it opens when a predetermined temperature inside of the exchanger is reached. If the exchanger overheats, the limit switch immediately turns off the gas flow to the burners. Without a functioning limit switch, a fire could occur, while an interrupted gas flow means that the furnace cannot provide heat.
The heat exchanger will shut down when the blower motor fails to work because the heat would otherwise build up in the heat exchanger. Of course, a blower motor can fail for many reasons, and one prevalent reason is improper belt tension. Another reason, and why seasonal HVAC maintenance is so vital, is an accumulation of dirt and debris in the motor housing and the fan cage. Some motors have a capacitor that can fail resulting in the motor not being able to reach the speed needed to push the air.
This is why a qualified, highly trained service technician should inspect the furnace to determine the reason for the heat disruption. This inspection requires skill and knowledge about the furnace, and it is a risk for the homeowner who attempts to diagnose and repair the problem on their own.
Some modern furnaces have a control panel that will send a diagnostic code when heated air cannot flow through the ducts. This control panel is one very good reason to look at a new furnace if your current furnace is older than 10 years.
High quality furnace and heater repairs in Cincinnati is what Pinnacle Air Solutions is known for. If you are in need of furnace repairs or furnace installation, please call us at 513.984.HEAT (4328) or use our contact form to send us a message.