Air Conditioner Compressor

• The air conditioner's compressor is the heart of the unit. It is the component that drives the refrigerant through the system. Typically, the compressor is installed outside the home in the condenser cabinet. It is a large, black, cylinder that makes most of the noise when the air conditioner is in operation. Some compressors have sump heaters that remove refrigerant from its oil. This prolongs the life of the unit.
  
  

Condenser Coil

• The condenser coil is the part of the air conditioner that sits outside the home. It is a large box with a fan on top. When the AC system is in operation, the condenser coil removes the heat from the refrigerant by blowing air across its radiator. Some condenser coils use water to cool the refrigerant and are located inside the home. These units are rare due to the amount of resources they consume.
  
  

Evaporator Coil

• The evaporator coil is located in the supply plenum of the HVAC system. This is inside the duct work, just above the furnace. When the air conditioner is in operation, it cools the house's air as it is blown past its coils. As the air cools, it releases some of its moisture, which is collected in a condensate tray below the evaporator.
  
  

Burners

• In a gas or oil furnace, the burner is located inside the cabinet below the heat exchanger. Its job is to combine fuel with the right amount of air and provide a point of combustion. There are many styles of burners, including ribbon, monoport and multiport burners. When operating properly, they burn fuel in the ideal environment.
  
  

Heat Exchanger

• The heat exchanger is the heart of the furnace. The exchanger allows the transfer of heat from the burners to the house's air without allowing the products of combustion to enter the home. It is located above the burners and is made from a variety of metals. Modern, high-efficient furnaces have long, wavy heat exchangers that slow the combustion products' movement to remove as much heat as possible.
  
  

Blowers

• The blower is located inside the furnace cabinet and draws the house's air into the return duct work, past the heat exchanger and back out the return duct system. The two types of blowers are belt-driven and direct-drive. They work similarly, except the belt drive has a belt in between the motor and the fan to transfer the rotational movement. A typical blower is 1/4 to 3/4 horsepower.
  
  

Distribution System

• In a forced-air HVAC system, the duct work provides the passageways to draw the unconditioned air to the furnace from the rooms in the house, then back again. These ducts are typically made from thin, galvanized metal. The supply registers should be located near exterior walls and under windows to provide conditioning in the ideal locations. The return registers are normally located on inside walls near the ceiling or floor.