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

When a technician reads zero Ohms between the common and low speed wires of a 120 VAC permanently split capacitor (PSC) furnace motor, it indicates that the low speed winding is shorted. A reading of zero Ohms implies that there is a direct connection (short) with very little to no resistance between those two points.

In a typical motor winding, you would expect to see a measurable resistance that reflects the winding's characteristics. A shorted winding means that the electrical path within the motor is compromised, leading to an excessive current flow that can damage the motor or create unsafe operating conditions.

The reading of zero Ohms signals a significant decrease in winding resistance; this is generally associated with a failure mode where the winding wires have either come into direct contact with each other or with another conductive material, resulting in a short. This condition would likely require motor replacement or repair to ensure safe and functional operation.