To clean the fins, turn the circuit breaker off and clean the unit’s fins with a garden hose. Use the most powerful “jet” setting but don’t use a pressure washer. If you’ve never done this before, you may get lots of crud out of the fins the first time. Keep washing the fins until the water runs clear.
Because of the compactness of some designs, you may have to get creative to clean the fins really well. But don’t take off any covers. Keep in mind that the only thing you are trying to clean are the aluminum fins. The compressor, electrical section and other parts don’t need cleaning and generally don’t like water. But since the circuit breaker is off, that shouldn’t be a problem (you did turn the circuit breaker off, didn’t you?). Also, don’t use any cleaner, just plain water.
Once the aluminum fins are clean, help keep them that way by not mowing around the unit when it’s running. When you do mow, discharge the grass clippings away from the unit.
Make sure there is nothing around the outdoor unit that blocks air flow. You don’t want shrubs or fences too close. The closest leaves should be at least two feet away and the center of shrubs and fences should be at least three feet away. You might not think this spacing matters very much but it does. We replace systems all summer that were killed by shrubs and wooden fences. The spacing you must have is much more than your eye will suggest. Shrubs should be cut way back, cut down, and cut out. Wooden fencing should be very open (80%). You’d be surprised at how much impact a few shrubs or fence slats can have on air conditioners. They block air flow, increasing electricity costs, cut cooling capacity and can damage the compressor.
Resource: Hvac contractor Charlotte NC