I think the plumbing is by far the hardest part. Electrical is pretty easy. Hard to screw that up. But if you screw up the refrigerant lines, they will leak ov

I think the plumbing is by far the hardest part. Electrical is pretty easy. Hard to screw that up. But if you screw up the refrigerant lines, they will leak over time, and your machines will not only stop cooling and the motor will burn out, but HVAC personnel who are licensed to buy refrigerant and re-charge your lines will refuse to work on DIY lines because they then will incur legal liability. I installed my own and paid an HVAC company to very my connections were good, and when it came time to release the refrigerant into the lines, the guy told me I had to do it for legal liability reasons.