What valve is used to control excessive pressure entering the compressor during a hot pull down?

The crankcase pressure regulator (CPR) is designed to maintain appropriate pressure levels within the compressor's crankcase. During a hot pull down, where the system is initially subjected to high temperatures and pressures, the CPR plays a crucial role. It prevents excessive pressure buildup in the crankcase, which can lead to serious operational issues or compressor damage.

By regulating pressure, the CPR ensures that the compressor operates efficiently and safely, allowing for smoother functioning as the system transitions to its normal operational state. This function is particularly important during the initial phase of cooling, where high pressure could adversely affect the compressor's performance.

In contrast, the head pressure regulator manages the pressure of the refrigerant in the condenser, while the evaporator pressure regulator focuses on maintaining steady evaporator pressures for proper cooling. The oil pressure regulator governs oil distribution and pressure but does not directly address excessive pressures in the crankcase. Each of these other regulators serves a specific purpose, but in the context of controlling excessive pressure entering the compressor during a hot pull down, the crankcase pressure regulator is the most relevant choice.