yeah "cold" a/c is subjective.
Case in point, certain Kubota I've had in the shop numerous times for "warm a/c" (that is the usual complaint on the r/o). Vent temps in the FORTIES, after running about 30 minutes. Obviously it's not going to get cold immediately. A lot of new cars have much more expensive and intricate a/c systems, e.g., variable displacement compressors, etc. They get cold quicker because of marketing. In other words, if one manufacturer says "my a/c gets cold faster than theirs", they have a marketing advantage. Anyway, back to my M series. After 3 or 4 times of checking it, I found nothing out of the ordinary other than the first time it had a plugged condenser (in between teh fins, not the screen--it was perfectly clean). I am honestly at that point dumbfounded, I mean I could get the cabin into the 70's really easily and it would maintain it. So finally instead of letting the service manager make the phone call to the customer, I called him myself from my personal phone, while inside the tractor, and told him get up here & see if this is acceptable. He shows up a couple hours later, hops in the tractor and goes to drive around. I had a hidden thermometer in the cab. He drives around for maybe 45 minutes and comes back & says nope still "hot". I grabbed my thermometer (which showed 78 degrees, and it was 98 outside) and showed it to him. He said that it's not acceptable. I asked why. He said he keeps his house a/c on 66 degrees. The cars (all climate control digital setting) set to 66-68 degrees. Well my God no wonder! Wuss. What tractor operator needs the a/c so cold that frost is forming on the windows? That's ignorant. As soon as you have to get out of the tractor you're blown away by heat, you're out in it for a few minutes, then you get back into that 68 degree cabin and you're spoiled.
20 degrees. That is the maximum temp drop that any a/c should reach. IOW, if it's 100 outside, figure that your air conditioner is going to struggle to get it below 80 inside. consider yourself lucky if you can get it lower.
air conditioners are designed to cool the cubic footage of the cabin, and no more. That means when it's really really hot out, you are going to struggle to get it "cold". That's been an issue with every tractor since the beginning of air conditioned cabins. John Deere a/c cabs are horrible, at least all the ones I've been in are.
Someone mentioned moving the a/c from the top to under the seat. I personally think it's easier to deal with under the seat rather than having to get up on a ladder & work over the top. Makes it a little less expensive to manufacture too (less hoses, cables, wires, etc). Makes a lot less mess when the time comes to have to clean the evaporator out too. Just remove it, it's on flexible hoses, pull it to the side and rinse. If it's in the top, you have to be really careful about getting water/cleaner/etc on the headliner and inside the cab. I have to line the entire top of the tractor with plastic and even then use lots of caution. Takes longer=costs more$$$.
Out here if you try to get the cab down much below 80 this time of year, you will have severe condensation developing on the windows. Right now the dewpoint is 76. At night it gets up around 78 or so. For instance this morning I was fishing on the river, and the water temperature was 64 degrees, and the fog was so thick along the water and up to about 30-35 foot above the water, that I could not see the front of my little 15' boat. Thats what happens to tractor windows too when the a/c is turned down below the dewpoint. Windows fog up and then you can't see no more.
Tinting the windows DOES help. Kubota doesn't do it because of liability. No tractor manufacturer does it to my knowledge (for liability reasons). You don't have to spend $1300. You can get it done cheaper. Also, worth mentioning, optional is to remove the top of the cab (the big orange plastic piece) and flip it over, then line it with some frost-king duct insulation. That seems to help big time. Combined with tinted windows, I bet one could get the cabin temp way down.