What does it mean when the limit switch is open?

What does it mean when the limit switch is open?

Limit switch codes If the furnace failure code indicates an “open limit” or “open high temperature switch” or “open rollout switch”, it is probable that the furnace has overheated. Limit switches turn off the burner and turn on the circulating fan if there is a high temperature condition in the furnace.

How do you reset the limit switch on a furnace?

How to Reset a Furnace Limit Switch

  1. Locate your furnace’s heating duct.
  2. Locate the white limit switch.
  3. Look at each arm to identify the settings.
  4. Identify the component (setting) located in between the two arms.
  5. Set the temperature on the middle component to approximately 105 to 115 degrees Fahrenheit.

What does open high limit mean?

An open high limit error on a furnace means the heating system turns off the fuel to prevent overheating. Ultimately, it is a key safety component of your furnace. A high limit error could be caused by Poor Airflow from the furnace.

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.

What conditions can cause the limit switch to open during furnace operation?

A high limit switch will keep tripping due to a dirty flame sensor, short cycling, obstructed airflow, or a defective switch. These lead to overheating within the gas furnace that triggers tripping as a safety measure to prevent fires. Clean and replace dirty and worn-out parts to fix the problem.

What does a primary limit switch do on a furnace?

The primary limit switch is a temperature-activated sensor that protects your furnace from overheating whenever the fan fails to blow enough air over the heat exchanger. The limit switch also controls when the blower assembly turns on and off.