How to Check an Overload Protector on a Central Air Conditioner

The electric motor in a central air conditioning unit is equipped with an overload protection switch. If the motor is overloaded, causing it to overheat, the switch reset button pops out from its seat and shuts off the power to the motor. When the motor has cooled sufficiently, you can restore the power and the air conditioner will once again function. You can check the overload protection on your central air conditioner with basic electrical know-how.

Step 1

Turn off the electrical power to the central air conditioner. If there is an external switch outside the home near the unit, set the switch to the “Off” position. Otherwise, turn the circuit breaker assigned to the unit off at the main electrical panel of the home.

Step 2

Open the electrical access panel on either side of the of the air conditioner. The panel will be marked for electrical access. Remove the panel screws counterclockwise with the appropriate screwdriver.

Step 3

Test the L1 and L2 posts on the terminal bus to verify that the power is off. Touch one probe of a voltage tester to the L1 and the other probe to L2 to perform the test.

Step 4

Locate the overload protection reset button on the motor. If it is not immediately visible, place your hand around the body of the motor to feel for it.

Step 5

Check the overload protector to see if the reset button has popped up. If it has, it will extend from the motor body approximately 1/2 inch.

Step 6

Press the reset button in until it is fully seated.

Step 7

Restore power to the air conditioner and turn the thermostat on to engage the unit. Allow the air conditioner to operate for approximately 15 minutes.

Step 8

Replace the side access panel and secure it in place with the screws. Turn the screws clockwise with the screwdriver.