One way to make sure your air conditioner stays in good shape is to have a professional come in for a maintenance appointment every year before the cooling season. This might seem like an unnecessary expense, but it can keep you from having to actually pay to repair your air conditioner, which can be very expensive and annoying. Besides this, keeping up on your air conditioner maintenance can keep the whole system clean, and it can give you some notice about when things might need replaced. That way, you can at least see it coming when an expensive repair might be in your near future or when you might need to replace your air conditioning system.
Another way to keep your AC in good shape is to run it less often. Throughout the summer, you can go easy on your air conditioner by setting your thermostat up a little bit higher, which can also save on your energy costs, of course. Besides this, you can keep your south-facing windows covered by curtains or blinds, which can help keep your rooms much cooler even without the air conditioner.