It is considered illegal to install a mini split air conditioner without an hvac contractor. Most of the air conditioner manufacturing companies will void the warranty if their system is installed without an hvac professional. This is basically due to the fact that the manufacturer would not want to be liable in case you try and install the system and end up hurting yourself. Installing mini split air conditioners consist of a few hazardous steps that might be dangerous if the person lacks experience/knowledge. For example, if you do not the pressure guage for the lines, yoou might end up creating pressure concerning issues. Hence, always contact an havac contractor for installing your system. That being said, you can always do the handyman related work to reduce the cost for hiring an hvac contractor.