Some Common terms explained:
Split system: the condenser and compressor are outdoors, the rest is inside
Package units: It is all installed outside.
Compressor: This is the heart of an air conditioning or heat pump system. It is part of the outdoor unit and pumps refrigerant to meet the cooling requirements of the system.
Condenser coil (or outdoor coil): In an air conditioner, the coil dissipates heat from the refrigerant, changing the refrigerant from vapor to liquid. In a heat pump system, the coil absorbs heat from the outdoors.
Expansion valve: regulates refrigerant flow into the evaporator
Condenser Fan: The fan that circulates air over the air-cooled condenser.
Air Handler: An air moving and/or mixing unit. Residential air handlers include a blower, a coil, an expansion device, a heater rack and a filter. Heaters for air handlers are sold as accessories. In some models heaters are factory installed.
Drain Pan: Also referred to as a condensate pan. This is a pan used to catch and collect condensate (in residential systems vapor is liquefied on the indoor coil, collected in the drain pan and removed through a drain line).
Freon: Freon is the cooling agent used in most air conditioning systems. Every air conditioning system needs a refrigerant (also called a coolant) that actually creates the cool air — that’s the role of Freon. Currently most new units use R-410A instead of the older R22, which has doubled in price in early 2012.
Capacitor: simple devices used in most HVAC equipment to assist compressors and motors with starting and running effectively. During the hot summer months many capacitors in outdoor units fail at a high frequency rate.