All air conditioners have four basic components: pump, evaporator, condenser, and expansion valve. Hot refrigerant vapor is pumped at high pressure through the condenser, where it gives off heat to the atmosphere by condensing into a liquid. The cooled refrigerant then passes through the expansion valve, which lowers the pressure of the liquid. The liquid refrigerant now enters the evaporator, where it will take heat from the room and change into a gaseous state. This part of the cycle releases cool air into the air-conditioned building. The hot refrigerant vapor is then ready to repeat the cycle. Other parts of an air conditioning system are fan, motor,capacitor,air handling unit, and drainage system and pan.