Filters and parts
Check with the retailer if they sell filters and parts or where you can get them from for the air conditioner as some brands are based overseas and it may be difficult to find spare parts or to repair the unit. An air conditioner with a cleanable re-usable filter is most ideal as you can simply remove the filter, clean it then pop it back in to the unit without having to purchase a new one.
Choose a system with the lowest running costs as electricity prices are always on the rise. While an expensive air conditioner unit may be pricey the running costs will be lower and more economical for you in the years to come.
When installing an air conditioner, energy efficiency is an important aspect that should be thought through to save money on running costs and excess energy consumption. Factors such as good insulation under roofs, as well as in ceilings and walls, will contain the cool and hot air from the air conditioner. Also the direction of the window in a room will affect the temperature. For example a west-facing window may be getting the afternoon sun when it's the hottest time of day in summer. Also air conditioners with inverters and "auto" settings are economical in power consumption because they automatically adapt and maintain the temperature you want.
There are two types of filters; to save on cost you may want one that is permanent as opposed to disposable. Most air conditioners have disposable filters and these should be replaced with the same size filter as originally supplied. Permanent filters should be cleaned according to the manufacturer's instructions. Regular cleaning and maintenance of filters in an air conditioner will increase overall efficiency of the unit and cut energy costs. Ideally the filters should be cleaned or replaced every few months.
Life expectancy and long term costs
After around 10 years, if the air conditioner starts having problems that are not cost-effective to fix, it may be time to replace it. Generally it is a good idea to replace the entire system (not just the indoor or outdoor unit) when a major component of the system fails to operate correctly and cannot be repaired. That's because air conditioning and heating units are designed to operate as a complete, matched system.