Excuse the newbie question......besides cahnging my furnace filter in the summer, is ther any general maintenance I can do on my outside central air unit? Stuff like claning the outside, etc.? Just like everyone else it seems, we are having a heat wave. I have a unit that faces the west and is not sheltered from the sun in any way. Just want to make sure it is operating as efficient as possible and has no problems in the heat wave.