What is the purpose of a disc-type control in a loss-of-charge shutdown scenario?

The primary function of a disc-type control in a loss-of-charge shutdown scenario is to prevent shutdown due to small leaks. When refrigerant leaks occur, a drop in pressure can result, which might not be substantial enough to trigger other safety devices. The disc-type control is designed to detect minor drops in refrigerant charge levels and provide a mechanism to maintain system operation, thereby ensuring that the system does not shut down completely due to these small, potentially manageable leaks. This capability helps maintain functionality and avoid costly interruptions in service, allowing for monitoring and addressing leaks before they become significant issues.

The other options pertain to different functions within an HVAC system. Regulating power supply is typically managed by dedicated electrical controls and circuitry. Providing backup pressure is relevant for different types of system controls, particularly in hydraulic systems rather than refrigerant systems. Maintaining consistent operating temperatures involves other mechanisms like thermostats and sensors, which monitor and adjust for temperature changes rather than focusing on refrigerant charge levels.