Remove the air conditioner from the window.
Depending on the size of the air conditioner its best to take it out of the window if possible. Some air conditioners that cool large size rooms can be very heavy. Once removed you can take it outside in close proximity to a garden hose.
When removing the faceplate there are a few screws that you have to remove to pull of the faceplate. If your room air conditioner has knobs on the front remove those too. Remove the faceplate and wash it using a garden hose to spray out all the dust and dirt. When you’re done you can wipe it down with a magic eraser. Rinse the faceplate and let it sit in the sun to dry.
Remove the filter. Most air conditioner filters can be cleaned. You can use a hose or compressed air and make sure it gets cleaned thoroughly. Older window air conditioners had replaceable filters, but no matter which one you are cleaning, make sure to replace or clean the filter so no dust or dirt remains. If you spray it with water allow it to dry before re-installing.
Cleaning the air conditioner unit. The easiest and most thorough method is to spray the coils with a garden hose. Avoid spraying the motor (wrapping a plastic bag around the fan motor can help keep it dry) although the fan motor is typically sealed and water won’t get inside. Dust and dirt makes the unit work harder and use more electricity. The unit will cycle more often when dirty which can cause blown fuses and circuit breakers.
Once you have cleaned the coils wipe the unit down and put it back together. Allow it to dry before replacing it in the window, over night is ideal. Once you turn the unit on, you will notice the difference in how much colder it gets, and the fact the compressor will cycle on less frequently.