Dear Jim: When my central air conditioner conks out, it is always on one of the hottest days. What is the best way to pick a good repair contractor? Is there any preseason maintenance I can do myself? — Barb H.
Dear Barb: An old central air conditioner or heat pump does typically conk out on the hottest days. This is because it is running almost nonstop to keep the house cool. Also, the efficiency and cooling output of the unit drops as it gets hotter outdoors, putting even more strain on the old compressor, especially the bearings and valves.
Finding a good contractor to repair or replace an old air conditioner is important because you expect your system to keep running for a long time after the repairs. The refrigeration system in an air conditioner is a complicated piece of equipment. You have no way to determine if things are set properly, so you have to trust that the contractor did it correctly.
When selecting a contractor, first check with your relatives and friends about whom they have used and their satisfaction. Also, when a contractor gives you a list of references, you should call each one. People often are afraid to offend a “nice guy” contractor, so they do not tell them of problems. They will, however, share any negative experiences with you, which will help you make your hiring decision.
If you do not have a source for contractor names, check with the Air-Conditioning Contractors of America (ACCA) and the Sheet Metal and Air-Conditioning Contractors’ National Association (SMACNA). Reputable contractors will belong to one or both of these organizations, which can give you a list of members in your area.
When installing a new system, the contractor should do a thorough analysis of your house and calculate its cooling needs. This should involve more than just measuring the outside dimensions and then recommending the same size unit as you have now. 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 various rooms. Additional return air registers and ducts may have to be installed. This can increase the overall cost significantly, so the lowest estimate is not always the one you should select.
If your system has just broken down and you have at least three contractors to give you quotes, be wary of ones who immediately want to replace the system with a new one. They should take the time to determine the current problem and provide a quote for repair.
Take your time to evaluate the quotes and recommendations. Although your family might be uncomfortably warm for several days, don’t rush your decision. It is not as dire as having your furnace go out during winter when your water pipes may freeze if not fixed immediately.
There are several maintenance tasks you can do each spring to keep your air conditioner running efficiently, but don’t eliminate regular professional service. Heating and cooling systems are no longer simple devices. They are packed with electronic circuit boards and controls, meaning you would have no way to test them without specialized readouts and training.
Having adequate airflow through the outdoor condenser coils is imperative for good efficiency and a long life. This is where the hot refrigerant expels its heat to the outdoor air. If the airflow is impeded and reduced so the refrigerant does not cool as designed, it can throw off the entire functioning of the system.
Make sure there is a foot or two of clearance around the housing where the coils are exposed to the outdoor air. This may require trimming back a few shrubs or not stacking things like junk and garden tools against the outdoor unit.
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. Make sure all the screws on the housing are tight. This ensures that air is being drawn through the coils and fins.
Change the indoor filter regularly. Switch off the electricity to the unit and remove the cover over the indoor blower unit. Clean dust off the blower and any evaporator coils you can reach with the vacuum brush attachment. Adequate indoor airflow is also important for good efficiency. Seal any leaking duct joints, and close the bypass damper for the humidifier.