Step 4 · Test the Upper Thermostat

This is the step most people slow down on. Take it one move at a time — there’s no rush, and you can rewind the clip as many times as you need.

Take a photo of the wiring. For a standard upper thermostat, testing occurs in two parts. First, test the high-limit switch. Set the multimeter to continuity (Ω symbol or sound icon). Disconnect the wires from terminals 1 and 2 (left side). Touch a probe to each terminal. A reading of 0 ohms (or a beep) indicates continuity. No continuity (OL) means the thermostat is bad. If it passes, reconnect the wires. Next, test the temperature control switch. Disconnect the wires from terminals 3 and 4 (right side). Test for continuity between them. A reading of 0 ohms means it's working. No continuity means the thermostat is bad and needs to be replaced. Remember to reconnect all wires after testing if the thermostat is good.