When testing a gas furnace, what indicates a potential issue with the furnace's electrical circuit?

When testing a gas furnace, a reading of 0 volts indicates a potential issue with the electrical circuit. This is crucial because gas furnaces rely on electrical components for ignition, control of the blower, and communication between various parts, such as the thermostat and the control board. If there is 0 volts measured in the circuit, it suggests a failure in electrical supply or a break in the circuit, which can prevent the furnace from operating properly.

A proper electrical supply is essential for the ignition sequence to initiate, which is critical for the heating process. Therefore, achieving a voltage reading of 0 volts often signifies that the furnace will not function, leading to heating failures that could be caused by blown fuses, tripped breakers, or faulty wiring.

The other options may indicate operational issues that are not directly tied to electrical circuit problems; for example, inconsistent flame color can suggest combustion or gas supply issues, frequent cycling may indicate a malfunctioning thermostat or system design flaws, and normal temperature levels do not signal electrical circuit issues but rather suggest that the furnace is functioning correctly in terms of heat production.