What indicates an open start winding when testing compressor windings?

An open start winding in a compressor is indicated when there is an infinite resistance (∞) reading between the run winding and the start winding, which means that there is no continuity in the start winding circuit. In this context, a reading of infinity from R (run winding) to S (start winding) confirms this condition.

In the scenario presented, the correct response shows that the resistance reading from R to S is infinite, which accurately shows that the start winding is open. At the same time, a reading of 4 ohms from R to C (common) indicates that the run winding is still functioning and has continuity. This combination of readings clearly identifies the failure of the start winding while not impacting the functionality of the run winding.

The other scenarios do not align with the characteristics of an open start winding. They display finite resistances between different windings or indicate continuity where it should not exist if the start winding was indeed open.