Not advocating MrCool, but they are DIY and a couple of these will get you in the same cooling range as what is there currently. They are very efficient and reasonably simple to install. 2 of these will give you about the equiv. of 6 tons of cooling and some redundancy... The efficiency is very good on these units. If MrCool isn't ideal, there are a handful of fully DIY mini-split unit options. Most will require a vacuum pump, but the MrCool units and a couple of others don't require the lines to be pumped.
36000 BTU MrCool
