The new AC is in a very large bedroom upstairs. It is one that I had not tried before - a Central Air unit. Temperatures downstairs have been around 35c (as they are today) when AC is not used. The upstairs temp was MUCH higher than downstairs before installing the new AC. Right now, it is 41.1c outside at 16:42.
Upstairs, after months without AC, the 3 outside walls in the bedroom were very hot, and obviously radiated heat into the room. Those walls have cooled down (a lot) since the installation, no longer feeling as hot. During the non-AC months, the bedroom floor (roughly 6.5 metres wide x 18 metres long) also became very warm to the touch, and was also acting as a giant radiator. That too has now cooled down since the AC installation. As the walls and the floor are now cooler than before, it takes less time for the air temperature to reduce inside the room when the AC is on.
There is only a very small roof overhang (around 1 meter), and there are 2 x 60cm windows, 2 x 1.2 m windows, and 1 2.4m patio door in the bedroom, which has sunshine from dawn to dusk, so it is easy to see why the bedroom suffered oven-like temperatures pre the new AC installation. It is much more comfortable now (even with the AC switched off in the day until bedtime.)
Relief at last!