What does a reading of 0 Ohms between the common and low-speed wires on a 120 VAC furnace motor indicate?

A reading of 0 Ohms between the common and low-speed wires on a 120 VAC furnace motor indicates that the winding is shorted. Typically, a winding should exhibit a certain resistance that is greater than 0 Ohms, which reflects its operational integrity. A reading of 0 Ohms suggests that there is an electrical connection where there should not be one—essentially indicating a short circuit within the winding itself.

In a properly functioning motor, readings would indicate resistance that signifies a complete winding circuit without shorts, and an open winding would typically show infinite resistance, not 0 Ohms. Therefore, having a 0 Ohm reading signifies that the motor has a fault, which is inherent to the winding rather than indicating it is simply defective in a larger sense; rather, it is presenting a specific wiring issue.