How do you reset the fan limit on a furnace?
How to Reset a Furnace Limit Switch
- Locate your furnace’s heating duct.
- Locate the white limit switch.
- Look at each arm to identify the settings.
- Identify the component (setting) located in between the two arms.
- Set the temperature on the middle component to approximately 105 to 115 degrees Fahrenheit.
Where is the furnace fan limit switch?
Your fan limit switch is located inside the furnace panel cover, usually near the upper right corner. The fan limit switch is responsible for turning the blower on and off at the appropriate times.
At what temperature on the fan side of a fan limit control should the blower start running?
Once the fan limit switch has sensed that the air in the plenum is a suitable temperature (usually around 20 degrees above the room temperature) it engages the blower fan to distribute air.
How does a fan limit control work?
To put it very simply, the furnace fan limit switch is a control that tells your furnace’s fan when to turn on and off. So, when the furnace isn’t on, it tells the blower not to operate (and send cold air into your home) and when the furnace is on, it tells the blower to turn on and start circulating the warm air.
What causes limit switch failure?
If the supply air is too hot, the interior of the furnace overheats, which can cause damage to components. The limit switch trips when temperatures are too hot, effectively shutting down the system and locking furnace operation until the unit cools.
What is a high-temperature limit switch on a furnace?
A high-temperature limit switch, also called a fan limit switch or simply a limit switch, is an important device used in forced-air furnaces powered by gas or heating oil. Simply put, it senses the temperature of the furnace and tells the blower fan to turn on and off at the appropriate times.
Where is the fan switch on a gas furnace?
The mounting plate usually contains two or more terminals that receive control wires for the blower fan and the furnace’s gas valve. The location of the switch varies by the furnace model, but it is typically located in the hot-air supply plenum, above the combustion chamber or heat exchanger of the furnace.
What is combination fan and limit control?
Adjustable Fan / Limit control: A traditional-design adjustable combination fan and limit control (shown above) operates using a bi-metallic spring wound into a helix and inserted into the supply plenum. The Fan switch “makes” or closes to permit the fan to run when temperature rises to the FAN ON setting.
What is a furnace fan switch?
A fan limit switch is a component of a furnace system that determines when the furnace blower assembly for hot air turns on and off. Essentially, this means that it determines when the hot air should be blown through your ventilation system.