Auto A/C Terms - Glossary
High Side

Every A/C system is divided into sides. The low side starts at the expansion valve or orifice tube, includes the evaporator and the hose that returns from the evaporator to the compressor. Low side accumulators are also part of the low side of the system. On the other hand, the high side of the system starts at the compressor and includes the hose running to the condenser (that hose may include a discharge muffler too), the condenser and line that runs from the condenser to the expansion valve or orifice tube. That hose is commonly referred to as the liquid line because it is always full of liquid refrigerant. High side or liquid line receiver driers are also part of the high side of the A/C system.

The high side is also called the discharge side of the system because it starts with the compressor’s discharge of high pressure, high temperature refrigerant.

Also understand that every A/C system includes two other ‘sides’. They are the liquid and vapor sides. The high pressure side of the system includes both vapor and liquid refrigerant. When discharged from the compressor, the refrigerant is high pressure vapor. When that refrigerant cools in the condenser, the heat that it absorbed in the evaporator is removed and the vapor refrigerant condenses to a liquid and returns to the evaporator after passing through the expansion valve or orifice tube.