On a unit with a reciprocating compressor, what typically causes a frosted suction line?

A frosted suction line on a unit with a reciprocating compressor is typically caused by too much liquid refrigerant leaving the evaporator. This condition occurs when the evaporator is flooded with liquid refrigerant rather than allowing the refrigerant to completely vaporize before it reaches the suction line. When liquid refrigerant enters the suction line, it causes a drop in pressure and temperature, leading to frost accumulation due to the colder temperature on the line.

In this scenario, if there is an excess of liquid refrigerant in the system, it means the evaporator is not functioning efficiently, which can be due to other issues like improper sizing, restrictions, or malfunctioning components that prevent the refrigerant from fully evaporating before it moves to the compressor. This results in frost on the suction line, as the cold, liquid refrigerant cools the line excessively.

The other options reflect conditions that may cause different issues but do not specifically lead to a frosted suction line in the same manner. Shortages of refrigerant typically cause a lack of cooling efficiency and can lead to warm lines rather than frost. Low ambient temperature may not directly cause frost unless the system is also experiencing issues with refrigerant flow. High suction pressure usually indicates an overcharged system but does not