You can try resetting the furnace limit switch yourself if you have a newer model by turning off the furnace for 30 seconds and then turning it back on. However, if this does not work or the furnace repeatedly shuts down, calling heating experts to reverse or reset the limit switch is a good idea.
What causes a furnace limit switch to trip?
If the air inside your furnace gets too hot, the limit switch trips to prevent overheating. If the furnace high limit switch trips due to overheating, there is likely an airflow issue that is preventing proper air movement through the system. Check your air filter, and replace it if dirty.
How do I reset my furnace switch?
How to Reset an Electric Furnace
First, turn off the power supply to the furnace by turning off the breaker in the circuit box.Locate the reset button on the furnace and press it to reset the furnace. If the button is popped up, press it down.Return the cover to the blower compartment and turn the power on.
How do I know if my limit switch is bad on my furnace?
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 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.
How do you reset a high limit switch on a heater?
How to Reset Furnace Limit Switch. Once the problem affecting your furnace has been identified and corrected, you should reset your furnace to continue enjoying the warmth on your home. In most gas furnace, this is done by simply shutting off the power supply and turning it back on after 20 or so seconds.
What causes 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.
Should a furnace limit switch be open or closed?
The fan limit switch should be open when the furnace is off and full of cool air, so you should get an OL reading; if not, there’s a short, and the switch should be replaced. The high limit switch should be closed when the furnace is cold, so you should get a zero reading; if you get the opposite, replace the switch.
How much does a limit switch cost?
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 long does it take for furnace to reset?
Press and hold the reset button for about 30 seconds. Raise your thermostat to the desired temperature. This should ignite your furnace. If there’s no ignition, then it’s time to call a professional.
Where is the reset button?
Alternatively referred to as the reset switch, the reset button allows devices that utilize it, such as a computer or peripheral to be rebooted. Usually, the button is on the front of the device, next to or near the power button.
Why is the furnace blowing cold air?
If your furnace is blowing cold air in your home, this is a sign of an issue with the flame detector, gas supply, air filter, pilot light, or condensate lines. Many of these issues are able to be easily solved on your own by sanitizing or replacing components in the gas furnace.
How do you diagnose a bad 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 many limit switches are in a furnace?
Identifying the Limit Switch
The mounting plate usually contains two or more terminals that receive control wires for the blower fan and the furnace’s gas valve. It’s possible that your furnace will have two or even three limit switches that check temperatures at different parts of the furnace.
