Auto A/C Terms - Glossary
Liquid Line

A/C systems are not only divided into high and low pressure sides, they are also divided into liquid and vapor sides. The liquid line of the A/C system is referring to the line that runs from the condenser to the evaporator. It is always full of liquid refrigerant.

As refrigerant circulates through the A/C system, vapor refrigerant from the compressor is pumped into the condenser so that the heat can be removed. In the evaporator, the refrigerant absorbed heat from the hot air passing over it. The condenser will remove that heat. When the heat is removed, the vapor refrigerant changes state back to liquid refrigerant.

That refrigerant, exiting the condenser travels through the liquid line to the expansion valve. The liquid line may also include a receiver drier if a low side accumulator is not on the system.