Low-ambient controls are used to ______________?

Low-ambient controls are specifically designed to maintain high-side pressure when the outdoor temperature is low. This is essential in air conditioning systems that operate in climate conditions where external temperatures can drop significantly. When the temperature goes low, without these controls, the refrigerant in the system could not condense properly, leading to inefficient heat exchange and potential damage to the compressor. Low-ambient controls help prevent this situation by enabling the system to operate effectively even in cooler conditions, ensuring that the refrigerant pressure remains in an optimal range for the system to function properly and efficiently.

The other options do not accurately describe the primary purpose of low-ambient controls. While increasing system efficiency and maintaining low or high-side pressure could relate to system performance, the key function of these controls is specifically tied to managing high-side pressure in low-temperature conditions. Controlling noise levels is also unrelated to the main operational purpose of these controls.