The condensing pressure of the condensing unit for cold room is often very low, which makes the pressure drop at both ends of the expansion valve reduce, and causes the refrigerant obtained by the evaporator to be small so that the failure of the refrigeration system occurs.
In the refrigeration system, if the condensing unit for cold room is installed outdoors, the exhaust pressure (condensation pressure) of the system will be relatively low in winter (or low-temperature environment). This kind of situation is often more common in the north. For air conditioning, it is the same for other equipment (cold storage, etc.); too low condensation pressure will make the expansion valve unable to obtain enough pressure drop at both ends, and it is difficult to provide the evaporator with appropriate refrigerant. On the one hand, the cooling capacity of the system fails to meet the requirements, and on the other hand, it will make the system frequent low-pressure alarm and other failures.