Over time any machine or piece of equipment will wear out and start to break down more frequently.  Your car gets worse gas mileage as the years go by.  That old computer is slower and slower each month.  The same holds true for your home air conditioning unit.  As it gets older the efficiency drops off resulting in higher electric bills and poor temperature and humidity control.  But just like other equipment, homeowners can take steps to keep efficiency levels up and the air conditioning running as best it can for its age.

The efficiency of an air conditioning unit is measured in Seasonal Energy Efficiency Ratio or “SEER”.  SEER is calculated by taking the cooling output for a typical air conditioning season divided by the total electric energy input during the same season.  Air conditioning efficiency takes into account both the cooling capacity of the unit and the amount of electricity it uses.  The higher the SEER number, the more efficient the a/c unit is.  To keep equipment efficiencies improving, federal regulation sets minimum SEER ratings that manufacturers must adhere to when designing equipment (currently 13 or 14 depending on where you are in the United States). 

Advances in air conditioning design have brought very efficient cooling units to the market with efficiencies of over 20 SEER, but homeowners with older units may find very low SEER ratings of 10 or even 8 installed at their house.  The difference in SEER rating alone comparing an old 10 SEER unit and a new 14 SEER may be enough to justify a replacement of the equipment.  But take an old 10 SEER unit and add 15 years of wear and tear, that unit is likely using electricity at a 6 SEER rate and possibly not keeping the house very comfortable.  Homeowners in this situation have to make the decision to repair or replace.

An a/c unit uses refrigerant (sometimes called “Freon”) to cool the air in the house.  Refrigerant is pumped through an internal piping system removing heat from inside the house and rejecting that heat to the outside.  The air conditioning process not only reduces the indoor air temperature, but also removes moisture from the air bringing down humidity levels.  One of the more common problems facing very old units is their inability to maintain consistent indoor temperature and humidity levels.  As the internal components wear out, the unit’s ability to cool the air is diminished.  Older a/c units are susceptible to leaks in the refrigerant piping and as refrigerant leaks out, the unit keeps trying to cool and dehumidify the air, but without proper refrigerant levels.  You will notice something is wrong when it doesn’t feel comfortable inside even with the a/c is running full blast.  It may be cool, but the air is humid and clammy.  As refrigerant leaks out of the pipes, the system is not able to both cool and dehumidify.  All of the system energy is being used to cool the air, but not remove the moisture causing indoor humidity to build up.

The water removed from the indoor air drains outside through a pipe called a condensate drain line.  If the drain line is clogged or blocked, the water doesn’t drain and can collect inside the unit.  The puddle of water releases humidity back to the airstream and into the house.  Even a brand new, highly efficient unit can have a blocked drain line resulting in rising humidity levels and if left untreated, the water can overflow and cause water damage inside your home.

Whether the a/c unit is newly installed or many years old, there are things you can do right now to improve the equipment efficiency and performance.  For starters, make sure the filter is changed regularly.  Depending on how dusty your home is, you may need to change the filter monthly.  For less dusty environments and for units that aren’t run as often you could extend that to every other month.  Either way, a clogged filter is going to make the a/c unit work harder to circulate air and that extra work hurts efficiency and significantly reduces overall system performance.

Over time, the outdoor portion of the air conditioning unit can become overrun with plants or covered with leaves, sticks, and mud.  These obstructions prevent the condenser fan from being able to smoothly pull outside air across the condenser coils and discharge heat to the atmosphere.  Clearing away debris and cutting back space around the unit will immediately help the system run easier.  If there is a hose nearby, gently spray off any mud stuck to the coils to improve airflow across the outdoor coils.  Anything you can do to improve airflow around the condenser will have an immediate payoff in the energy efficiency of the unit and its ability to cool and dehumidify indoors.

Of course, the simplest and best way to keep the unit’s performance as high as possible is to have it serviced regularly by a licensed and reputable heating and air conditioning contractor.  A service technician can handle the filter change, coil cleaning, and look for refrigerant leaks.  They’ll know how to get deep into the equipment to look for worn or failing parts and find other ways to tune up the unit to improve performance.

In older homes with very low SEER air conditioning, there comes a point where the unit is so electrically inefficient that, even if it’s working properly, the electric bill savings along is worth the cost of replacement.  If the technician advises a replacement ask what options there are for high efficiency units, humidification and dehumidification systems, or programmable thermostats.

The age, efficiency, and performance of an air conditioning system are all interrelated.  As a/c units age, efficiency and performance drop off leading to poor temperature and humidity control and higher utility bills.  When homeowners notice that indoor comfort levels are not what they should be, it’s time to do a little DIY checking and cleaning of the equipment.  However, for older air conditioning units with low SEER, poor indoor conditions and high electric bills, these problems might only be solved by getting a new a/c unit. Work with a local a/c service company to understand what steps you can take to bring your aging unit back to life or have a new high efficiency system cooling you down this summer.