How To Test High Limit Switch

A high limit switch is a temperature-sensitive device used to prevent a furnace from overheating. It is usually located near the blower compartment and is wired in series with the heating elements. The switch will open when the furnace temperature reaches a certain point, which interrupts the flow of electricity to the heating elements and stops the furnace from running.

How To Test High Limit Switch

There are different ways to test a high limit switch. One way is to use a multimeter. Set the meter to continuity and touch the probes together. If the switch is closed, there will be continuity. Another way is to use a solenoid valve. Close the valve and turn on the power. The valve should open. If it doesn’t, the switch is bad.

A multimeter, a screwdriver, and a high limit switch.

  • Touch probes to each wire
  • Turn breaker off
  • Remove wires from old switch
  • Remove cover plate touch probes to each wire turn breaker on

-Check the continuity of the switch. -Check the resistance of the switch. -Measure the current flowing through the switch.


Frequently Asked Questions

How Do I Know If My Limit Switch Is Bad?

If your limit switch is bad, your furnace or air conditioner will not turn on. To test your limit switch, turn off your furnace or air conditioner and disconnect the power. Remove the limit switch from the furnace or air conditioner and test it with a multimeter.

What Happens When A Limit Switch Goes Bad?

If a limit switch goes bad, it will likely stop working entirely. This could cause the machine it is attached to to stop working or malfunction in some way.

How Can You Tell If A Limit Switch Is Bad?

If a limit switch is bad, it will not respond when it is activated.


To Review

Testing a high limit switch is a fairly simple process. The first step is to locate the switch, which is typically found near the heating element of the furnace. Once the switch has been located, it can be tested by using a continuity tester or multimeter.

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