By Mike McClintock, Special to Tribune Newspapers
August 16, 2010
Invest the time to improve air conditioner efficiency (or the money for a service call), and the triple reward is cooler air, lower utility bills and longer appliance life.
Some improvements require a service tech with specialized equipment, for instance, to detect small leaks in refrigerant lines and recharge the system to full capacity. That's often the problem when an air conditioner seems to run longer than it used to while maintaining temperature. But most maintenance is basic cleaning, applies to central systems and room units, and does not require special tools. In either case, check the manufacturer's recommendations and disconnect the power before starting any work inside the unit.
Call a pro
Here's a checklist from Trane, a major AC manufacturer, covering the key jobs you should expect in a thorough service call for system maintenance. It applies to central air systems and heat pumps that handle heating and cooling.
Check operation in cooling and heating modes, including the refrigerant level and defrost operation on a heat pump.
Check and clean indoor and outdoor air conditioner coils, the blower housing and blower wheel.
Inspect control box wiring, clean any debris inside the cabinet, and check that the base pan drain is unobstructed.
Check the duct system for leaks that lose cool air in unconditioned spaces like attics or crawl spaces.
Clean or replace the filter. Fan motors on modern systems are permanently lubricated and don't need periodic oiling.
Trane, for one, encourages owners to do preventive maintenance like basic cleaning and changing filters. And if you discover a problem in the process you can always call for service. For instance, if it seems that one room is much warmer or cooler than others, a service tech can use sensitive instruments that measure the temperature and airflow at registers to pinpoint the trouble.
For room units that don't have major problems like a clunking compressor, maintenance is even easier.
Inside, remove the grill and clean the finned coils of pipes with a vacuum cleaner, or wipe them with a soft brush. The fragile, closely spaced fins increase cooling efficiency by expanding the surface area of pipes carrying refrigerant. If you compress them while cleaning, efficiency can plummet.
Outside, remove the grill, clean the pipe coils, and check the drain in the base of the enclosure. Condensation that drips into the pan should flow out freely, or the collected water becomes stagnant. Once a year, it's a good idea to rinse the pan with a disinfectant, such as a 50-50 mix of household bleach and water, or a cleaning solution recommended by the manufacturer.
More cleaning caveats
Some of the easy jobs, like washing down condenser coils, come with caveats. Homeowners have become used to the fast action of pressure washers. But even their lowest setting is often too much for exterior grills and will practically pulverize the aluminum fins around pipe coils.
According to Trane, you should also avoid the flow from a garden hose at normal household pressure of about 50 pounds per square inch. The company says there's too great a risk of electrical shock when you turn the power back on and wires in the control box are still soaked.
Blitzing a washable filter is OK because you can remove it to clean it. But it's safer to clean the coils of room or central units with a vacuum or compressed air. With air cleaning, blow from the inside to force out dust and debris the way it came into the coils. If you decide to clean with a hose, also spray from the inside out, and shield electric components with plastic bags. Allow several hours of drying time before you reconnect the power.