Follow these instructions to maintain the a/c .
Remove the air conditioner from the window and clear away any accumulated debris from the windowsill. Take the appliance out of its cabinet. (Some will slide out of the cabinet, but on most, the cabinet is held in place with screws.) Remove the screws and put them aside (Fig. 3). Then, use a shop vacuum and crevice tool to get rid of leaves and debris from within the air conditioner (Fig. 4).
To clean the inside (Fig. 5), bring the appliance outdoors and use a paintbrush and some soapy water. Put plastic bags over the fan motor, electrical control box and compressor. Secure the plastic with duct tape. Hose the inside clean (Fig. 6), and make sure the base, coils and pan for condensate are clean as well.
When you've finished, remove the plastic bags and dry off the air conditioner with a fresh cloth. Allow the remaining moisture to evaporate, or you can accelerate the drying process by blowing out moisture with a can of compressed air. Single-use cans of compressed air are available through tool catalogs and some hardware stores. You can also try using a rechargeable air tank, which is sold at hardware stores, home centers and auto parts stores.
When the appliance is dry, reassemble and reinstall it in the window, following the general guidelines mentioned below. It's a good idea to allow the air conditioner to remain idle for one full day--just to be sure that the machine is thoroughly dry before you begin running it.