Our central air units keep us cool during some of the most oppressive heat of the summer. Keeping them clean ensures that they work well and will also extend their working lives. Central air units frequently get clogged with dust and other debris they extract from the air. They must be checked and maintained regularly. The good news is that you don't need any expensive or fancy cleaners to keep your central air until working. All you need is something most of us keep in our kitchens--vinegar.
Remove the central air unit from the wall sleeve, or unscrew it from its current location. If the unit is permanently fixed, then remove the outer casing to clean the unit.
Cover all of the switches in the front with duct tape. Take the clear plastic, and cover the motor. Use the duct tape to hold the plastic in place. This will protect some of the more delicate parts from getting wet.
Take your spray bottle, vinegar and water. Mix ½ water and ½ vinegar inside the bottle. Shake the solution well, and apply it to the evaporator coil and condenser coil. It is fine to give it a good soaking. Allow some of the solution to drip away, and wipe away the remaining solution with the cleaning rags. Vinegar will not harm the parts and is a very effective cleaner. The dust should come away quite easily. If, after cleaning, you still find a fair amount of dust and debris, an all purpose oven cleaner may be needed.
Repeat the same procedure with the evaporator blower wheel. Make sure to wipe all the solution away. Clean the caps on top of the fan motor ports the same way. The ports themselves will likely have to be cleaned out with compressed air. This can be done now or at a later time.
Let the parts dry, and reassemble the unit. Remove all plastic and duct tape from the motor and the outside switches. Place back in the wall sleeve or former location, and switch it on. You should notice a marked difference in how well the unit works. Repeat this procedure once per month during the summer to keep your central air unit working efficiently.