Yes, you can install a mini-split on an interior wall. This is something for which you will want to have a professional come to your house to see what the most energy-saving & cost-effective way is to install your ductless mini-split system. The HVAC technicians at Mac 5 Services are trained to help answer all of your ductless mini-split installation questions. They will come to your home and give you a competitive, comprehensive quote for your mini-split installation.