If a compressor start winding resistance test shows OL, which conclusion is most accurate?

If a compressor start winding resistance test shows OL, which conclusion is most accurate?

• A. The winding is open
• B. The winding is shorted
• C. The winding is normal
• D. The winding has partial shorted turns

Answer: (A)

When you see OL (open) on a resistance test across the start winding, it means there is no continuous path for current—the winding is open. In other words, the copper winding circuit is broken somewhere, so the ohmmeter can’t find a closed circuit. This is why the winding cannot provide the initial torque the compressor needs. If the winding were shorted, you’d expect a very low or near-zero reading because some turns are creating a direct path with less resistance. A normal reading would match the expected finite resistance value for that winding. A winding with partial shorted turns would usually show a resistance that is not open but is abnormal (often lower than normal) and would also typically cause overheating or poor performance.

When you see OL (open) on a resistance test across the start winding, it means there is no continuous path for current—the winding is open. In other words, the copper winding circuit is broken somewhere, so the ohmmeter can’t find a closed circuit. This is why the winding cannot provide the initial torque the compressor needs.

If the winding were shorted, you’d expect a very low or near-zero reading because some turns are creating a direct path with less resistance. A normal reading would match the expected finite resistance value for that winding. A winding with partial shorted turns would usually show a resistance that is not open but is abnormal (often lower than normal) and would also typically cause overheating or poor performance.