In an A/C system performance test, what could indicate a defect in the high-pressure cutout switch?

When assessing the performance of an A/C system, the high-pressure cutout switch serves a crucial safety function by preventing damage to the compressor and associated components. If the high-pressure cutout switch is defective, it may not function as intended. This could lead to the situation where the A/C compressor continues to operate despite excessive pressure in the system, potentially causing overheating, compressor failure, or damage to the refrigerant lines.

In a properly functioning system, the high-pressure cutout switch should disable the compressor when high pressure is detected, stopping it from running further. Therefore, if the compressor keeps running when pressures are unacceptably high, it indicates that the switch is malfunctioning.

Understanding the other options sheds light on why they do not indicate a defect in the high-pressure cutout switch. For instance, if the compressor stops running, it might be responding correctly to high pressure or other issues rather than indicating a fault in the switch. Low refrigerant levels could also be a separate problem affecting system performance, but it does not directly reflect the high-pressure switch's condition. Normal pressures on all sides suggest that the system is operating within its designed parameters and does not indicate any defect.