The Costs. The average cost to install a mini-split air conditioning system is $1,900. The maximum average cost to install a mini-split air conditioning system is $2,100.The minimum average reported cost for mini split-air conditioner installation is $1,700.Continue reading to see more cost considerations for all mini-split air conditioning systems.urthermore, proper insulating must be done to maximize energy efficiency. When hiring an HVAC company or contractor to install a mini-split air-conditioning system, there are some specific factors that must be taken into account. The cost of the unit itself usually ranges between $1,100 and $1,400.