How to Test a White-Rodgers AC/Heat Thermostat

Thermostat Heater Testing

• 1

  Turn off the circuit breaker to the AC/heating unit.

• 2

  Remove the cover of the thermostat. Some models of White-Rodgers thermostats pull straight off, while others have two screws that must be removed first.

• 3

  Insert a small flat-head screwdriver into the screw holding the red wire in the thermostat. Turn the screw counterclockwise, until the wire is free from under the screw. Grasp the red wire with one hand, and wrap it around the center of a pencil at least twice. Release the pencil so that it straddles the hole in the wall where the red wire comes out. This keeps the loose wire from entering in the wall.

• 4

  Loosen the screw holding the white wire counterclockwise, with a small flat-head screwdriver. Grasp the white wire, once it is loose from under the screw.

• 5

  Hold the white wire in one hand, and unwrap the red wire from the pencil with your other hand. Twist both bare copper ends of the wires together. Release the wires, and turn on the circuit breaker to the AC/heating unit.

• 6

  Turn up the thermostat's temperature to its highest setting, and set it on heat. Listen for the blower motor to start, and then feel near one vent for heat. If your blower turns on and there is warm air exiting the vent, the thermostat is faulty.

Thermostat A/C Testing

• 7

  Turn off the circuit breaker to the thermostat.

• 8

  Wrap the red wire around a pencil to keep it from entering the wall. Replace the white wire under the screw in the thermostat, and tighten it clockwise with a small flat-head screwdriver.

• 9

  Remove the green wire from under its screw, and test the AC portion of the thermostat by connecting the green and red wires together. Turn on the circuit breaker to the AC/heat.

• 10

  Turn the thermostat to the lowest temperature, and set it to cool. If the blower starts and cool air comes out from the vents, the thermostat is faulty.