A/C Thermostat Test

1.Connect battery power to the No. 3 terminal, ground the No. 2 terminal, and connect a test light between the No. 1 and No. 3 terminals.

NOTE: Use a 12 V, 3 W-18 W test light.

2.Dip the A/C thermostat into a cup filled with ice water, and check the test light.

  • The light should go off at 3°C (37°F) or less, and should come on at 4°C (39°F) or more.
  • If the light doesn't come on and go off as specified, replace the A/C thermostat.