When an air conditioning system is running,
are blowing air across the evaporator and condenser coils. Inside the house, we use the furnace fan if there is one. If there is no forced-air heating, we put in a separate fan to move air across the coil and through the ducts. Outdoors we put a fan in the cabinet with the condenser and compressor. The
in an air conditioner are heat exchangers although they are not normally referred to as such. Their function is to transfer heat from the house air into the refrigerant inside and to move heat from the refrigerant into the outdoor air.
is the vehicle that collects from the house, moves it outside and releases it into the outdoor air.
in the condenser cabinet is squeezing a cool, low-pressure gas into a hot, high-pressure gas. The expansion device (capillary tube or thermostatic expansion valve) near the evaporator coil is converting a hot, high-pressure liquid to a cool, low-pressure liquid.
Some people talk about the
sides of an air conditioning system. The high-pressure side is from the discharge side of the compressor, through the condenser coil, through the liquid line and up to the expansion device. The low-pressure side is from the expansion device, through the evaporator coil, and out through the suction line to the inlet side of the compressor.
The larger copper tube (
) that carries the cool low-pressure gas from the evaporator coil out to the compressor is insulated. This is because we do not want to dump more heat into the gas as we move outside. Remember, we are trying to dump heat from inside the house to the outdoors, not collect outdoor heat.
The other reason to insulate the suction line is to prevent sweating on the pipe. This gas is cool, relative to the house air and the outside air. If uninsulated, it would have condensation all over it. When you are looking at an operating air conditioner, you should check to see that the large suction line is cool to the touch any place where there is no insulation. If there is condensation on the small uninsulated sections of the pipe, that is fine. You do not want to see frost; that indicates a problem.
The uninsulated copper line (l
) coming from the condenser coil back into the house contains a warm liquid. It is smaller than the suction line which carries a gas. This is logical because gas takes up more space than liquid. Because this smaller line carries a warm liquid, when the air conditioner has been running for fifteen minutes or so, this line should feel warm to the touch.