Air conditioning coils perform less efficiently as they become dirtier. A gradual buildup of sediment inhibits the cooling process and lowers the useful lifetime of the unit. Regular maintenance and cleaning can solve both of these problems.
Basic Coil Cleaning
The coils on an air conditioner are very delicate, and damaging them can cost plenty to repair. The first "cleaner" that should be tried is water from a garden hose. Direct the spray at the coils and rinse them thoroughly. Use a brush with soft bristles to work out any clogged debris.
Soft Scrub DIY Cleaner
If a plain stream of water from the hose doesn't work, a gentle cleaner should do the trick. You can make a soft scrub mixture by combining any liquid soap with baking soda. This will provide enough grit without excessive harshness. You can purchase a brush specifically made to clean AC coils, a soft brush of your own or a soft brush attachment on a vacuum cleaner.
Prevention and Solution
Bending the soft metal coils or the venting fins of an AC unit can greatly reduce its functionality. Be as cautious as possible, and if the job looks like too much, call in a professional HVAC mechanic. If you do damage the fins, special brushes to straighten them are available.