The Refrigeration Cycle: The Heart of Cooling Commercial air conditioning works on the same fundamental principle as a refrigerator, using a refrigeration cycle to extract heat from the air: Evaporation: A liquid refrigerant passes through an evaporator coil. Warm air from the building is blown over this coil, causing the refrigerant to evaporate and absorb heat from the air. Compression: The gaseous refrigerant is compressed, increasing its temperature and pressure. Condensation: The hot, high-pressure refrigerant travels to a condenser coil. Outside air is blown over the condenser, releasing the heat from the refrigerant, causing it to condense back into a liquid. Expansion: The liquid refrigerant passes through an expansion valve, reducing its pressure and temperature, ready to start the cycle again.