With proper maintenance and care a ductless systems should perform for over 20 years. Many of the systems installed during the 1980’s are still functioning well today. The average cost of an installed ductless systems with a single indoor heating/cooling zone is between $3,000 and $5,000.Additional heating zones and greater heating capacities will increase the cost of the system.his entry was posted in Air Conditioning Ductless mini split system Mitsubishi Mini Split Systems and tagged Mitsubishi Ductless Mini Split System Mitsubishi Electric Mitsubishi System on March 17, 2015 by developer14sa.