If you have an air conditioner, you have a suction line–that’s the “cold” copper line that runs between the compressor and the evaporator, and it carries the cool refrigerant back to the compressor to be turned back into liquid. When your HVAC system is new, this line is insulated air-tight with 3/4″ insulation. AS TIME passes, this insulation breaks down, and you can see gaps and tears in it. These gaps allow the cold refrigerant vapor inside to absorb ambient heat from the room or outdoors. This is not desirable, because this heat then becomes part of the work your air conditioner has to do, costing you both more electricity to run your a/c unit as well as lost cooling capacity. A third harm is that when the suction line becomes warmer, there is less cool gas coming back to the compressor, and your compressor runs hotter, which shortens the life of your compressor. So the next time you are looking over your air conditioner, look at the large, insulated line and make sure the insulation is in good condition. If not, and you are a handyman, you can probably do this yourself. Or if you have better things to do, ask your HVAC professional to reinsulate the suction line. Either way, it’s money well spent.