It happens usually on a hot summer weekend: Your air-conditioning unit stops working. You can take several steps to ensure a longer life for your unit without spending a lot of money.
Keep it clear of debris. The key component of your home's AC system relies on the coils within the unit remaining free to cool the incoming air. Remove weeds and grass, and be on the lookout for insects. Switch off the electric power. (This switch can be found inside the breaker box inside.) Remove the sheet metal screws and lift off the housing.
Remove the debris and use your garden hose to spray off the coils. Do your best to avoid the electronics. Inspect the coil fins if they are bent. Straighten them as well as you can with the tip of a sharp knife. Replace the housing and carefully tighten all screws.
Check for ants. They are a dangerous intruder. Seeking water and shade, ants will take up residence in your air conditioner, costing you hundreds of dollars. Deter ants by using an exterminator, or try using Lysol spray. (They do not like the smell of Lysol.) Or use white vinegar to wipe away the dust a few times a week. Install ant traps or try surrounding the unit with baby powder, chili powder, scouring powder, boric acid, borax or salt, creating a barrier.
Try to put your AC unit in a shady place. Consider putting up a lattice screen for air circulation. Be sure to not put it too close to the unit, and be sure to build it in a way to allow access for maintenance.