Potential problems can be avoided by having heating and cooling equipment checked annually, and by keeping furnace filter(s) clean. Fewer dust particles can accumulate on the evaporator coil when the filter is changed regularly. The evaporator coil is a refrigerant filled system of copper tubing designed to receive heat from air molecules. When higher temperature air molecules come into contact with lower temperature copper tubing, heat is released. A build up of dust particles on the evaporator coil impedes the transfer of heat. Clogged filters also hamper efficiency by restraining air flow through the system, which causes equipment to work harder than necessary. Strain on equipment adds to your utility bills because more energy is used to meet the increased demand. The accumulation of pet hair can quickly clog a filter and increase the need for more frequent changes. Air conditioners also require attention for efficient operation. There should be two feet of clearance around the unit for air to properly circulate around it. Unnecessary strain on an air conditioner can be avoided by keeping the area free of leaves, grass clippings, and plants.