I have an uninsulated garage with cinder block walls. They're painted on the outside and bare on the inside. Eventually, I'm going to insulate and you FF's have already advised me on the best way to do that. Before I do that, I want to install an opening for a large through-the-wall air conditioner. The wall I'd like to do this on is a load bearing wall about 32' long and 8' tall. There is a pressure treated 2x6 lying on the flat side along the top of the top course of blocks for the floor joists above (attic space) and rafters to sit on. I can punch out blocks with an air hammer I have relatively easily. I also have a spud bar and sledge hammer if I need to use them. I do not have a concrete saw and I'm not sure I really need one for punching out blocks and mortar for one opening. I realize I'll need one of those steel lintel plates going across the top of the opening to keep the above blocks from collapsing down, but I'm not sure how I'd go about installing one. For ease of closing things up, I'll probably frame the opening with pressure treated 2x8's so I can slide the AC in and secure it no problem.