It's All About the Cleaning
The average ductless mini split air conditioner, with proper care and maintenance, will have a lifespan of 12 to 15 years. If you live in an area with high humidity or salt, your system may not last quite as long. The best maintenance you can provide your system is cleaning it. Clean and change your filters. Not only will you prevent breakdowns and freeze-ups, but you will enhance the ability of the system to purify the air in your home. Most air handlers have tabs to take out filters to clean and/or change easily. For your compressor, take the garden hose and wash it down well several times during the season of use.
Caution: When servicing your system, especially when using water, shut the power off.