Basics of Refrigeration Cycle in HVAC for Architects. Evaporator Unit along with Supply Air Fan is placed in the Room which is to be Cooled. Supply Air Fan throws the Warm Room Air drawn from the room over the Evaporator. Warm Air passes over the Chilled Liquid Refrigerant present in the Evaporator and Cooled Air is passed in the Room. Compressor & Condensing Units are placed Outside for Cooling Hot Refrigerant by Ambient Air.