Will a window unit actually work with these leaky sliding barn doors?

Single-hose portable ACs are basically self-defeating in a shop like yours becasue they create negative pressure. Every cubic foot of hot air they blow out that hose is being replaced by hot, humid air sucked in thru those gaps in your barn doors. You're effectively trying to cool the entire outdoors. Switching to a **window unit** will help significantly because it recirculates the indoor air instead of venting it out, but it’s still going to struggle against those leaky doors.

Sliding barn doors are notorious for being impossible to seal. Since you can't swap them out, you need to look at **industrial brush seals** or weatherstripping meant for garage doors. You can mount these along the top track and the vertical edges where the door meets the jamb. Even a heavy rubber flap at the bottom can stop the "chimney effect" where your cold air just spills out onto the slab. If there's a massive gap where the two doors meet in the middle, an overlapping astragal is your best bet to close that light gap. As for the insulation, you’re right that cold air sinks, so the open ceiling isn't the primary disaster for cooling that it whould be for heating. But that roof is likely radiating a ton of heat directly onto you. Even if you don't want to finish the walls, tacking up some **radiant barrier foil** or thin foam board between the rafters can stop that heat soak without ruining your storage space. It makes a massive difference in how the air actualy feels on your skin. Go with a window unit rated for at least 10,000 BTUs. The dehumidification alone will make an 85-degree shop feel like 75. Just don't expect it to stay cool once you turn the unit off. Without insulation, the thermal mass of your tools and slab will bounce right back to ambient temp the second the compressor stops.

I had this exact setup in my old shed. Those barn doors are basically sieves. What actually saved me wasn't just the window unit—it was hanging a set of thick PVC strip curtains right behind the doors on the inside. It lets me slide the doors open but keeps the "cold bubble" from dumping out the bottom.

I threw a 12k BTU unit in the wall and it dried the air out enought that I stopped sweating trough my shirt in ten minutes. If you don't seal those gaps, you're just cooling the driveway, but the strips are way easier than trying to get brush seals to line up on wonky barn doors.

Have you ruled out the track stand-off distance? Most barn door hardware is designed to keep the door an inch or two away from the wall to avoid scuffing. If that's your setup, even a massive window unit is going to struggle because you've got a permanent air gap you can't easily seal. Also, are you sure the doors are actually hanging plumb? If they're tilted even slightly outward at the bottom, all your cold air is just sliding out like water under a gate. Before you buy a new AC, maybe check if the doors are even capable of a tight fit.