Fan limit switches are used in various heating systems to control the operation of the blower fan. Honeywell is one of the leading manufacturers of fan limit switches, known for their reliability and durability. In this article, we will discuss the wiring diagram for Honeywell fan limit switches and provide some frequently asked questions to help you understand their functions better.
What is a Fan Limit Switch?
A fan limit switch is a safety device that controls the operation of the blower fan in a furnace or other heating system. It is designed to prevent the system from overheating and causing a fire by shutting off the blower fan when the temperature inside the furnace reaches a certain level.
The fan limit switch consists of two parts: the fan switch and the limit switch. The fan switch turns on the blower fan when the furnace heats up, and the limit switch shuts off the fan when the temperature reaches a certain level.
Wiring Diagram for Honeywell Fan Limit Switches
The wiring diagram for Honeywell fan limit switches is straightforward and easy to follow. The switch has three terminals: the fan terminal, the limit terminal, and the common terminal. The common terminal is connected to the power source, while the fan and limit terminals are connected to the blower motor and the limit control circuit, respectively.
| Terminal | Function | Color |
|---|---|---|
| Common | Power Source | Black |
| Fan | Blower Motor | Blue |
| Limit | Limit Control Circuit | Red |
To wire the switch, follow these steps:
- Turn off the power to the furnace.
- Disconnect the wires from the old fan limit switch.
- Connect the black wire from the power source to the common terminal on the new switch.
- Connect the blue wire from the blower motor to the fan terminal on the new switch.
- Connect the red wire from the limit control circuit to the limit terminal on the new switch.
- Turn on the power to the furnace and test the switch for proper operation.
FAQ
1. What is the purpose of a fan limit switch?
The purpose of a fan limit switch is to control the operation of the blower fan in a heating system and prevent overheating.
2. How do I know if my fan limit switch is faulty?
If your blower fan is not working or is making strange noises, it could be a sign of a faulty fan limit switch. You can test the switch using a multimeter to check for continuity.
3. Can I replace my fan limit switch myself?
Although it is possible to replace a fan limit switch yourself, it is recommended to hire a professional to ensure proper installation and avoid any potential hazards.
4. What is the difference between a fan switch and a limit switch?
A fan switch turns on the blower fan when the furnace heats up, while a limit switch shuts off the fan when the temperature reaches a certain level to prevent overheating.
5. How often should I replace my fan limit switch?
It is recommended to replace your fan limit switch every 5-7 years to ensure proper functioning and avoid any potential hazards.
