To clean the inside of the unit, first turn off the electrical power to it. Check for an on-off switch on the unit or on a separate box nearby. Remove the grille from the unit and carefully remove the fan in order to gain access to the coil and other moving parts. At this point, you should be able to clean out any debris from inside the unit using your hands. You can also use a vacuum hose to remove debris. A soft brush or cloth rag can be used to other areas of the HVAC unit.
The fins on the coil require a gentler approach as they can be easily bent or damaged. If you notice a bent fin you can straighten it out by using a simple dull knife or a special fin “comb” which you can buy at your local hardware store. While you are in the unit, check the fan belt on the motor to ensure it is not damaged or cracked. You can also add extra oil to lubrication ports on the condensing unit, if any are available.
Use a garden hose to clean the coil and the grilles on the condensing unit. Do not use highly-pressurized water as it may cause some damage to the fins. Once this last task has been completed, reinstall the grille, switch on the condensing unit, and start up your air conditioning. You should notice if your house is cooling down quicker. If not, you may want to do some more cleaning.