An induced draft motor is not operating when the thermostat is calling for heat. What would be the MOST CORRECT test to make?

When an induced draft motor is not operating while the thermostat is calling for heat, performing a voltage check on the circuit board at the induced draft motor terminals is the most relevant step to diagnose the issue. This approach helps to determine whether the circuit board is sending the appropriate voltage to the motor. If voltage is present at the terminals, it indicates that the control system is functioning correctly and that the problem likely lies within the motor itself or its associated components.

By checking the voltage at the terminals specifically for the induced draft motor, you can ascertain if there’s power reaching the motor when it should be operating. If there is no voltage present, this suggests a potential issue with the control board or the wiring, while detection of voltage prompts further testing of the motor itself or its referenced circuitry.

The other options, while useful in specific circumstances, don’t directly target the immediate concern of verifying power to the induced draft motor. For instance, checking the thermostat’s voltage may not reveal information about the operation of downstream components. Similarly, performing a continuity test on the motor addresses the motor's functionality but does not assess if the motor is being powered as intended. Testing the flame sensor is unrelated to the operation of the induced draft motor and addresses a different part of the heating