Posted: June 29, 2009

When summer’s heat waves deliver hot, humid weather, homeowners can give thanks for the cool, calm influence of air conditioning.  The period from July 3 to August 15 is designated as Air Conditioning Appreciation Days.  So it’s fitting, while relaxing in a perfectly chilled and dehumidified room, to raise iced teas in a toast “to acknowledge the contribution of air conditioning to a better way of life.”

It’s easier for homeowners to keep vital air conditioning systems running smoothly with some knowledge of typical operating problems.  Offering advice to homeowners on common central air conditioning problems is Tom Weiss, president of Tom’s Dependable Heating & Cooling, Inc. in Greenfield and a member of the Milwaukee/NARI Home Improvement Council, Inc., the area's leading home improvement and remodeling industry resource for more than 47 years.

A main way to avoid chronic air conditioning problems is to choose a system of the right size.  Contractors take into account the size of the home, the amount of insulation, the size of the ductwork running throughout the home, and also the age and type of windows in the house.

Getting a system of the proper size is critical because if it’s too small, the machine will work very hard to keep up, which will affect how long it lasts. If the air conditioning system is too large, it will short-cycle, which is to turn itself on and off constantly, and it won’t dehumidify the house properly.

Another common problem is a lack of air return vents, which sometimes are either not installed, or not installed in adequate amounts.  Without returning air, the blower motor will be suffocated and have to work a lot harder, creating a shorter lifespan and overheating.  It takes too much energy.  Also, turning the air over in the house will make the house evenly cool.

Other problems can arise during installation of a system if components, both indoors and outdoors, are not perfectly level.

The A coil sits on top of the furnace, encased in sheet metal, and it needs to be sitting evenly so there is uniform air flow.  If it’s sitting unevenly, part of the coil will freeze, and when it thaws out, it will leak water into the furnace.

It’s also important to make sure that the outdoor unit is completely set and leveled.  Milwaukee/NARI members suggest using a solid gravel base, then a concrete slab, to make sure it’s sturdy.  If it’s not sitting level, the bearings and the compressor will be working really hard and the outdoor unit will fail prematurely.

Weiss says the problem of frozen coils stems from airflow problems, which can be caused by a dirty filter, blocked ductwork, or low refrigerant.

Basic maintenance can be a solution.  Weiss states, “It’s a good idea to have your system checked annually, because refrigerant levels will be checked.”

He points out, “Many customers don’t realize they have to change the furnace filter in the summer, too, as the same ductwork is used for cooling and for heating.”  The most common cause of a dirty filter?  Pet hair.

Corrosion of wires and contactors, the switch that turn on the air conditioning unit, is a common problem for outdoor units.  Along with summer heat comes insects, and earwigs in particular are attracted to the contactors on the air conditioning unit.

When an earwig touches a contactor, it causes a spark or arc.  Every time it does that, it means the contactor loses a little more of the contact surface.  The contactors become corroded and pitted; they have to be sanded to restore a good contact area.  Weiss warns that a professional should be called to handle the high-voltage contactors.

“We probably replace 20 contactors a year,” he says.  “This is another item that can be taken care of in an annual checkup.  We either replace the contactor, or sand it and spray it with WD-40, because earwigs don’t like WD-40.”

If the central air system is making a noise, it’s not a fan belt problem.  Contrary to popular belief, furnaces built since the 1980s don’t have fan belts, so that’s not a noise issue.

Homeowners who cover the outdoor unit in the winter may want to cover only the top third.  This will prevent rodents from making nests but will allow needed air circulation.

When starting the system for the first time of the season, homeowners should check to see that the outdoor coil is clean.  If grass clippings or leaves are sticking to it, turn the thermostat off in the house and then spray the coil off with a hose.

If the outdoor unit fails to start, check that the electrical breaker switch for the air conditioner is on.  Although many homeowners turn the breaker off during winter, that is not necessary.

Greenfield-based Tom’s Dependable Heating & Cooling, Inc is a member of the Milwaukee/NARI Home Improvement Council, Inc., the area’s leading home improvement and remodeling industry resource for more than 47 years. For more information or to receive a free copy of an annual membership roster, call (414) 771-4071 or visit the Council’s Web site at www.milwaukeenari.org.