With winter on its way, it's time to put the air conditioner to bed for the season. You don't want to simply switch it off, or you may have trouble come next summer. The following tips can help you prepare your AC unit for winter. Simply find the section below that applies to your AC type.
Central AC with an outdoor unit
The standard option for many single family homes is the central air conditioning unit, which has an outdoor compressor and fan. This typically sits next to the home, although in some cases it is roof mounted. Prepping these units for winter is relatively straight forward. Begin by changing the AC filters inside the house and vacuuming any dust or lint out of the filter housing. Outdoors, you can remove the cover of the unit and vacuum out any leaves or other debris that has collected inside. Next, lubricate the motor and fan, using an owner's manual for your particular AC model to locate the proper lubrication points. Finally, remove the drip tray, if present, and rinse it with a bleach solution so mildew doesn't grow. Finish up by placing an AC cover over the top of the unit to protect it from ice and snow. A proper cover should only cover the top or the side should be vented to allow air circulation.
These are also sometimes called swamp coolers. They are popular in dry climates, like the US Southwest, or in areas with mild summers. Most often, an evaporative cooler is roof mounted, although there are some ground mounted versions. For winter, the unit needs to be shut down and the cooling pads need to be removed. Wait until the next cooling season before putting in new pads, since you don't want them to absorb winter moisture and to mold. Drain the water from the cooler and flush out all the water hoses with a bleach solution to prevent mildew and algae growth. Finally, shut the intake vents in your home, if your house is equipped with them. This way you won't be letting cold winter air inside.
Window air conditioners should also be cared for before winter. Generally, all you need to do is clean or replace the filters in the unit, and use a shop vacuum to remove any dust or debris from the fins on the outside of the unit. If your window AC is removable, bring it inside and store it somewhere dry. For permanently mounted units, use a tarp or an AC cover to wrap the exterior portion to protect it from the elements and to prevent drafts inside the house.
For more help, contact an air conditioning service in your area.