Which condition describes when the compressor should NOT be running during testing?

The correct answer indicates that the compressor should not be running when testing the oil indicator switch. This is crucial because the oil indicator switch is designed to monitor the oil level or pressure within the compressor system. If the compressor is operating during this test, it could lead to inaccurate readings and potential hazards, such as oil spills or pressure abnormalities, which might result in damage to the equipment or pose safety risks to the operator.

Testing components like the oil indicator switch while the compressor is off allows for a safe assessment of the system's condition without the risk of moving parts or pressurized systems interfering with the evaluation. This ensures that the readings being taken are solely based on the oil system's status without the complications introduced by the compressor’s operation.

In contrast, testing conditions for safety valves, checking for water buildup, and inspecting electrical connections can typically be conducted with the compressor either on or off, depending on manufacturer guidelines and safety protocols, as long as appropriate safety measures are followed.