The roof looks like a red hat. Inside the hat, all sorts of junk is hidden, like the outdoor units. It’s a powerful system with two installations working in parallel. One of them has a broken compressor, and in the other, the refrigerant has somehow escaped. We searched for a long time to find out where it went, but we couldn’t locate it. We need to pressure test the system by raising the pressure with nitrogen to detect any leaks or confirm that there aren’t any. We’re out of nitrogen, and we don’t have enough refrigerant to work on this unit. Plus, hauling it up to the roof—well, to the hat—on the third floor using rickety ladders, without any guarantee of success, doesn’t make much sense. We can’t really find any leaks, and then refilling it would be a hassle. We poured in the leftover refrigerant—7 kilos—just to get it working somehow. We still needed a couple more kilos, but at least it started cooling. It’s better this way; while this refrigerant leaks out, we’ll have time to come back. Otherwise, the clients won’t understand in the summer. We measured the air and ceiling temperature with a thermal camera: the ceiling is at 27 degrees, and the air is at 22. At least it’s something. We headed home, planning to return later.