While it can differ slightly from one furnace manufacturer to the next, you can find the high limit switch by removing the furnace cabinet cover. 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.
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.
Can you fix a limit switch?
Yes, it’s possible to replace a furnace limit switch yourself. To do it, you’ll first need to use a multimeter to test the switch. If it’s faulty, you’ll also need a new switch that matches your old one. Here’s how to test the furnace limit switch and replace it if necessary.
How do you reset a limit switch?
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 do you test a limit switch?
With the furnace in full operation, connect a digital voltmeter across the two connections of the limit switch. The voltage drop should be less than or a maximum of 0.1 VDC. The switch should be immediately suspect if the voltage drop is 0.2 VDC or higher (Fig. 1 indicates a bad limit switch).
How much does it cost to replace a limit switch on a furnace?
You’ll need to get a limit switch from the same company that makes your furnace. This component could cost anywhere from $4 to $25, depending on your original equipment manufacturer. At the lower end of this price range, you might like to buy a universal switch.
What is furnace high limit switch?
The high temperature limit switch (also known as a furnace plenum thermostat) is a safety device on a furnace that is designed to cut the gas supply when the burner temperature exceeds the safe operating range. When the temperature drops back within the safe range, it will allow the gas valve to open again.
How much does it cost to replace a high limit switch?
Average Cost of a New Furnace Limit Switch
You will need to buy a high limit switch that is produced by the same manufacturer as your furnace unit. Depending on who your OEM is, this component could roughly cost you anywhere from $4 to $25.
How do you know if a 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 reset the limit switch on a Trane furnace?
To access it, you’ll need to remove the front panel of the furnace. You may find that many models have limit switches where the reset button is located. The button is often located on top of the switch and will need to be pressed to initiate the reset.
Where is reset button on Trane furnace?
After the furnace cools, access the blower motor compartment. The compartment usually sits at the very bottom of the appliance. If you look inside the blower motor fan, you should find the reset button.
What will cause a limit switch to open?
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. On the left are some high temperature limits used in furnaces.
