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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.
Where is the fan limit control switch located?
The fan limit switch sits on a mounting plate and has a long temperature sensor that extends into the furnace plenum: an air chamber that fills with air from the blower fan. The plate has a wire that runs to the blower and one that goes to the gas valve.
How do I know if my fan limit switch is bad?
The most common sign of a malfunctioning limit switch is the continuous operation of your furnace’s blower. Just as the limit switch won’t allow the fan to turn on until the warm air has reached the right temperature, the limit switch also shuts down when the air cools to a certain temperature.
How do you change a furnace fan limit switch?
Step 1: Remove the Access Cover. Step 2: Locate the Limit Switch. Step 3: Conduct a Voltage Test. Step 4: Turn Off the Power. Step 5: Disconnect the Switch. Step 6: Unscrew and Remove the Switch. Step 7: Install a New Switch. Step 8: Replace the Furnace Cover.
Can you run a furnace without a limit switch?
Without a functioning furnace limit switch, a furnace would not be able to regulate the temperature in conjunction with a thermostat. Typically, a furnace limit switch consists of an exterior plate and a temperature probe that lives inside the furnace housing.
Where is the fan limit switch on a Lennox furnace?
Examine your furnace and look for a raised button or switch to the right of the ignition control box (or the “Limit Control” switch).
What happens when a limit switch goes bad?
One common symptom of a malfunctioning limit switch is a blower fan that doesn’t shut off. A bad switch also can prevent a furnace from operating at all. If the switch has completely failed and is stuck in the open circuit (off) position, the furnace won’t run. The same effect can result from repeated overheating.
Do all furnaces have a fan limit switch?
Fan/Limit switches are used on all types of building heating furnaces. CLICK HERE to see a CLOSE-UP [image] of the FAN OFF, ON, and HIGH LIMIT OFF factory settings on this fan limit control. 1- FAN OFF: the low temperature at which the furnace blower fan will STOP to prevent blowing cool air onto room occupants.
What causes a limit switch to open?
Limit switch codes The limit switch shuts off the burner when the temperature exceeds a preset temperature. When the temperature reduces to normal, the burner will come back on. The most common reason for limits to open is a plugged filter or a dirty blower wheel.
What is the symbol for a limit switch?
IEC Symbol Preview – Limit Switches Horizontal Symbol Vertical Symbol Description HLS11 VLS11 Limit Switch Normally Open HLS12 VLS12 Limit Switch Normally Closed HLS11C VLS11C Limit Switch, Roller Normally Open HLS12C VLS12C Limit Switch, Roller Normally Closed.
Where is furnace reset button?
Locate the reset button on the furnace and press it to reset the furnace. It is usually located inside the blower compartment on the side of the blower motor. Be cautious as the housing may be hot. If the button is popped up, press it down.
Why is my furnace fan not turning on?
Make sure that the power cord hasn’t melted or a fuse hasn’t been blown. If your cables are looking fine, try unplugging the fan for a few minutes and then plugging it back in again. If unplugging and plugging your fan back in again doesn’t work, check the fuse box.
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.
How does furnace limit switch work?
A limit switch is a device that’s located under your furnace’s supply plenum. It reads the temperature of the plenum and waits until it gets appropriately warm. If the temperature inside of the plenum gets too hot, it shuts off the gas supply to your burners to prevent your furnace and heat exchanger from overheating.
What is the function of limit switch?
A limit switch is an electromechanical device operated by a physical force applied to it by an object. Limit switches are used to detect the presence or absence of an object. These switches were originally used to define the limit of travel of an object, and as a result, they were named Limit Switch.
Are limit switches normally closed?
A limit switch may be normally open (NO) or normally closed (NC) in its normal resting position. A NO device, when actuated, switches to close (or “make”) the circuit, whereas an NC switch would open and break the circuit when actuated.
What is limit switch in electrical?
In electrical engineering, a limit switch is a switch operated by the motion of a machine part or the presence of an object. A limit switch can be used for controlling machinery as part of a control system, as a safety interlock, or as a counter enumerating objects passing a point.
