As far as the AC fitted to my 25year old disco I has 6c out of the dash vents even on the hottest days in the UK.
The disco was my first vehicle fitted with AC so interested in what it did, my fingers on the steering wheel felt they were freezing, the vent temp was less than the 6c today, so the system was switch off and later back on when I was in France/Belgium at the time, then the outdoors ambient temp at the time was 40c plus… it seems to get HOT over there in summer.
The discos AC system still has the refrigerant it had when it left the factory, so no leaks, possibly because its used summer & winter, it looks after the seals I understand
Now we have climate control i’m still playing with the AC dash control, I thought I could just dial the temps for both sides and that is that, but the system thinks differently.