Many refrigeration systems are installed using an outdoor air-cooled condenser. When these systems are installed in a climate where the outdoor temperature drops below 60°F, some means of preventing the condensing pressure from dropping too low must be incorporated into its design.
Too low of a condensing pressure results in too low of a pressure drop across the system’s TXV, which leads to reduced refrigerant flow through the TXV and a starved evaporator. This is not good for overall system operation.