In order to clean your AC condenser coil, you'll need the following tools: grass shears or pruners, spray bottle of coil cleaner, soft brush, fin comb, carpenter's level, pry bar or piece of 2x4 (0.6 x 1.2 meters), and gravel or rocks.
Most condensers are located outside your home and have a fan to move air throughout the condenser coil. As a result, it's easy for leaves, grass, dirt and airborne dust to get into the condenser, making it dirty and clogged. So the first step you want to take to keep your condenser clean is to prune or cut away any vines, weeds or plant obstructions that might be blocking airflow.
Then, use your coil cleaner (you can buy a bottle at a refrigerator supply store) to clean the coils. The commercial coil cleaner will have the specific instructions you should follow for that brand. You'll want to flush out the cleaner (don't use a hose) and let the coils dry.
Next, you'll want to clean the fins. The fins are usually pretty delicate as they're made of a light-gauge aluminum. Indeed, if you find the fins are bent, you can straighten them with a fin comb (you buy one at an appliance parts store). Use the soft brush to clean the dirt off the fins. Don't use a hose or water as that can just turn the dirt into mud.
The last step is to make sure the concrete slab the condenser sits on is level. Lay your carpenter's level front to back and side to side on top of the unit. If you find that the unit is not level, you can use the pry bar and/or rocks to raise it up where the unit needs to be lifted.
One of the best ways to clean your condenser is to prevent it from getting dirty in the first place. You can buy a commercial condenser cover to fit over your unit's condenser.