We all receive those advertisements in the mail for an annual air-conditioning system preventative maintenance checkup. Most licensed contractors send a qualified technician to your house to perform a basic preventive maintenance service and inspection. This type of service increases the air-conditioning system's life expectancy and improves its energy efficiency. Unfortunately, a few companies use these flyers as simply a way to get through your door with their "29-point checklist" and then look for a way to fix something. Many homeowners choose to avoid this hassle and give their own system its yearly preventative maintenance service.
Regularly changing the furnace filter increases the system's energy efficiency and lessens the workload on the system's components. A dirty filter makes the fan work harder, and in extreme cases, the reduced air flow across the evaporator coil freezes the condensation, forming an ice block that cuts the airflow even further. A missing, improperly sized, damaged or poor quality filter lets dust pass; where it then accumulates on the evaporator coil and blower wheel.
Manufacturers offer several different grades of filters and rate them on a MERV scale. Filters rated with a higher MERV, which stands for Minimum Efficiency Reporting Value, collect a larger percentage of the air-borne contaminants passing through the unit. Many homeowners choose filters with a MERV rating between five and eight.
Electronic air-conditioning filters neutralizes airborne contaminants that the system's disposable filter misses. This upgrade rarely needs repair or maintenance beyond washing the cartridges and pre-filters regularly.
When air passes over an air conditioner's evaporator coil, the coil lowers air temperature and turns the humidity in the air into condensation. The condensation flows down the coil's fins and gathers in the drip pan, where the water enters the drain line. The slow drip fails to create enough current to flush long drain lines, allowing sludge to form in the constantly wet section. Eventually, the sludge dams the drain line.
Some air conditioning systems utilize an emergency float switch. The switch connects in series with the thermostat's circuitry. A high water level in the drain pan makes the float switch open its contacts, turning off the air conditioning system.
An air-conditioning system's yearly preventive maintenance checkup should include one of three levels of evaporator coil cleaning: a yearly maintenance with a foaming aerosol coil cleaner, an in-place cleaning with a liquid coil cleaner, or when a licensed technician removes the coil from the furnace and gives it a chemical bath. Homeowners who properly change their furnace filter every month often never need anything more than a quick yearly maintenance clean. A coil with moderate buildup on the surface needs the in-place treatment and coils with excessive buildup on the surface and between the fins needs a chemical bath.
A liquid coil cleaner removes more debris than an aerosol cleaner, but not as much as a professional bath. As the liquid flows between the coils, it picks up debris that an aerosol cleaner would miss.
Most furnace fan motors run many years with little care other than a quick visual inspection of the electrical terminals and verifying the blower wheel spins freely. A few models require a touch of oil with every service. Fan motors with oil service ports require annual maintenance. The lubrication the oil provides keeps the bearings from overheating and limits surface wear.
A basic air-conditioning system's condensing unit contains a refrigerant compressor, fan, capacitor, high-voltage relay, and condensing coil. A basic heat-pump system's condensing unit also uses a defrost circuit board and reversing valve. Both types of systems sometimes have upgraded items such as a hard-start capacitor for the compressor and a timer that prevents the system from restarting too quickly, such as when someone moves the thermostat temperature lever up and down repeatedly.
© 2017 Bert Holopaw