The coldest air in an Air Conditioning System is in?

• A. Expansion turbine
• B. Compressor
• C. Condenser
• D. Evaporator

Answer: (A)

The cooling effect in an air conditioning system comes from the evaporator, where the refrigerant inside the coil is at its lowest temperature and absorbs heat from the passing air. As warm room air moves over the cold evaporator surface, heat is transferred to the refrigerant and the air is cooled—often to near the evaporator’s surface temperature. The expansion stage does lower the refrigerant temperature before it enters the evaporator, but the air itself becomes cold where it contacts the evaporator coil, not at the expansion point. So the coldest air is produced in the evaporator region.