If a technician reads 0 Ohms between the common and low speed wires on a 120 VAC furnace motor, what does this indicate?

Reading 0 Ohms between the common and low-speed wires on a 120 VAC furnace motor typically indicates a short in the winding of the motor. A reading of 0 Ohms suggests there is a direct connection, meaning the resistance between the wires is negligible. In a properly functioning motor, the resistance should be above 0 Ohms, indicating that the windings are intact and functioning as intended.

When a winding is considered "open," it means there is no continuity, and you would see an infinite resistance reading, not 0 Ohms. Therefore, 0 Ohms indeed suggests that there is an issue with the winding, typically identifying it as having a short circuit where the wire insulation might have failed, allowing the wires to touch.

Thus, if the technician is encountering 0 Ohms between these two points, it signifies that the winding is compromised, and further inspection or replacement of the motor may be necessary to restore proper function.