With the power shut off, clean out the leaves and muck at the bottom of the unit. A wet-dry vac is useful here. Make sure to clean the side openings for rain to run out and not build up inside.

Clean the fan blades with a cleanser and rag, taking care to get the tips of the blades, which can develop a dirty edge.

Check that the wiring is in good shape and not chewed by animals. Make sure that all wires have good, tight connection points.

Inspect the refrigerant line insulation, which can deteriorate over time. Replace insulation as needed to keep the heat pump operating efficiently.

Restore power when finished.