When your A/C conks out

Choose a good contractor and weigh the quotes
By James Dulley
When your A/C conks out

Air conditioning systems are complicated, so you need a technician for regular maintenance.

An old central air conditioner or heat pump will typically conk out on the hottest days, mainly because it is running almost nonstop to keep the house cool. The unit’s efficiency and cooling output drops as it gets hotter outdoors, putting even more strain on the old compressor, especially the bearings and valves.

Selecting a contractor

Finding a good contractor to repair or replace an old air conditioner is very important. An A/C’s refrigeration system is complicated, so you have to trust that the contractor does it correctly.

Check with your relatives and friends for references. Also, when a contractor gives you a list of references, call each one. Customers may be afraid to offend a “nice guy” contractor, so they do not tell them of problems. They will, however, share any negative experiences with you.

You can also check with the Air-Conditioning Contractors of America (ACCA) and the Sheet Metal and Air-Conditioning Contractors’ National Association (SMACNA). These organizations can give you a list of members in your area.

When installing a new system, the contractor should do a thorough analysis and calculate your house’s cooling needs. Improper sizing will result in higher utility bills and poor comfort level.

A knowledgeable contractor should ask if you currently have any heating and cooling problems, particularly with any rooms. There may have to be additional return air registers and ducts installed.

If your system has just broken down, be wary of contractors who immediately want to put in a new one. They should take the time to determine the current problem and provide a repair quote.

Take your time to evaluate quotes, even though your family might be uncomfortably warm for several days. It is not as dire as having your heating system go out during winter when your water pipes may freeze.

Annual maintenance

There are several tasks you can do, but don’t eliminate regular professional service. Heating and cooling systems are packed with electronic circuit boards and controls, and you have no way to test them without specialized readouts and training.

Having adequate air flow through the outdoor condenser coils is imperative for good efficiency and a long life. Make sure there is a foot or two of clearance around the housing. This may require trimming back a few shrubs.

If you notice that some of the heat transfer fins on the coils are bent over and touching so air cannot flow between them, separate them with the tip of a scraper. Don’t flex them too much or they may break off. They don’t have to look uniform to be effective.

Also, make sure the housing screws are tight to insure the air is being drawn through the coils and fins.

Always turn off the electricity to the unit first at the disconnect or breaker panel before working on it. The panel should be mounted on the outside of the house within a few feet of the outdoor condensing unit.

Change the indoor filter regularly. Again, switch off electricity to the unit and remove the cover over the indoor blower unit. Clean dust off the blower and any evaporator coils with a vacuum brush attachment. Adequate indoor air flow is also important. Seal any leaking duct joints with aluminum or duct tape and close the bypass damper for the humidifier.

About the Author

James Dulley is an engineer and syndicated columnist for the National Rural Electric Cooperative Association. www.dulley.com

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