Clean your outdoor unit on a day that’s at least 60 degrees F. That’s about the minimum temperature at which you can test your air conditioner to make sure it’s working. The condenser usually sits in an inconspicuous spot next to your house. You’ll see two copper tubes running to it, one bare and the other encased in a foam sleeve. If you have a heat pump, both tubes will be covered by foam sleeves.
Your primary job here is to clean the condenser fins, which are fine metallic blades that surround the unit. They get dirty because a central fan sucks air through them, pulling in dust, dead leaves, dead grass and the worst culprit— floating “cotton” from cottonwood trees and dandelions. The debris blocks the airflow and reduces the unit’s cooling ability.
Always begin by shutting off the electrical power to the unit. Normally you’ll find a shutoff nearby. It may be a switch in a box, a pull lever or a fuse block that you pull out (Photo 1). Look for the “on-off” markings.
Vacuum the fins clean with a soft brush (Photo 2); they’re fragile and easily bent or crushed. On many units you’ll have to unscrew and lift off a metal box to get at them. Check your owner’s manual for directions and lift off the box carefully to avoid bumping the fins. Occasionally you’ll find fins that have been bent. You can buy a special set of fin combs (from an appliance parts store) to straighten them. Minor straightening can be done with a blunt dinner knife. If large areas of fins are crushed, have a pro straighten them during a routine service call.
Then unscrew the fan to gain access to the interior of the condenser. You can’t completely remove it because its wiring is connected to the unit. Depending on how much play the wires give you, you might need a helper to hold it while you vacuum debris from the inside. (Sometimes mice like to over-winter there!)
After you hose off the fins, check the fan motor for lubrication ports. Most newer motors have sealed bearings (ours did) and can’t be lubricated. Check your owner’s manual to be sure. If you find ports, add five drops of electric motor oil (from hardware stores or appliance parts stores). Don’t use penetrating oil or all-purpose oil. They’re not designed for long-term lubrication and can actually harm the bearings.
If you have an old air conditioner, you might have a belt-driven compressor in the bottom of the unit. Look for lubrication ports on this as well. The compressors on newer air conditioners are completely enclosed and won’t need lubrication.