This step shows how to test the inlet thermistor. If you just need to replace the hi-limit thermostat or inlet thermistor, you can skip this step.

With the thermistor removed from the heater housing, test for resistance with the multimeter across the two small terminals.

The value shown (61.8 kΩ) is acceptable for a good thermistor at room temperature (68°F/20°C). The nominal range at this temperature is 61.2‑63.7 kΩ.

If the device shows outside this range, replace it.