What causes an open limit switch on a furnace?
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.
What causes high limit switch trip?
The high limit switch helps to protect the heat exchanger from getting cracked from excessive temperatures. If an excessive amount of heat builds up in your heat exchanger, your high limit switch will trip and shut off the burners. This is done to prevent the heat exchanger from cracking.
How do you reset an open limit switch 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.
Can I bypass a high limit switch?
Yes, you can bypass the high limit switch for testing.
Can you bypass furnace limit switch?
There is no good reason for a consumer to bypass a furnace limit switch. Furnace switches are reliable, inexpensive to replace, and are designed for protection of the consumer. Bypassing a furnace limit switch or any home heating component can create dangerous safety and fire hazards.
How many ohms should a limit switch read?
The meter should read between “0” and “0.1” Ohms. Remove the switch or at least disconnect the wires from it and connect an Ohmmeter-set it to the lowest possible range-across the switch.
Are limit switches Universal?
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 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.
Can you bypass a limit switch?
What happens when a limit switch goes bad?
Limit Switch Malfunctions One common symptom of a malfunctioning limit switch is a blower fan that doesn’t shut off. This happens when the switch fails to shut off after the burners have stopped and the air exchanger is sufficiently cool. A bad switch also can prevent a furnace from operating at all.