When checking the windings on a compressor, what do readings of R to C = ∞ and S to C = ∞ suggest?

When checking the windings on a compressor, readings that show resistance from R (run winding) to C (common) as infinity (∞) and from S (start winding) to C as infinity (∞) indicate that there is no continuity in those windings. This suggests that the circuit is open, meaning the electrical path is broken and current cannot flow.

Specifically, the reading of ∞ from R to C indicates that the run winding is not completing the circuit, which is critical for the compressor to operate. Similarly, an infinity reading from S to C indicates a lack of continuity for the start winding, suggesting that the start winding is also not functional.

This scenario aligns specifically with the notion of an open start winding, which prevents the compressor from initiating operation as it cannot receive the current required to start. Therefore, the interpretation that these readings suggest an open start winding is accurate.

It's important to note that a grounded compressor or an open internal overload would typically produce different resistance readings, while a functional system would reflect continuity in both windings showing readings well below infinity. Thus, the readings obtained directly point to the condition of the start winding being open, stopping the compressor from functioning correctly.