An infinity reading on an ohmmeter between high and low speed wires on a 120 VAC furnace motor indicates what?

When an infinity reading is obtained on an ohmmeter between the high and low speed wires of a 120 VAC furnace motor, it indicates that there is an open circuit in the winding. This means that there is no continuity between the high and low speed wires, suggesting that the winding is not complete.

In a properly functioning motor, you would expect to see a certain resistance value (not infinity) indicating that the windings are intact and allowing current to flow. Additionally, a reading of infinity means that electricity cannot pass through, signifying that there might be a break in the wire or a failure within the motor's winding itself. This open condition can prevent the motor from operating in either speed, which is critical for the furnace's operation.

Understanding this helps in diagnosing issues with motor functionality and is essential for HVAC technicians in maintaining and troubleshooting gas heating systems.