It looks to me as though the system is doing exactly what you tell it to. During the weekdays you have it set constantly to 23C, which it seems to be meeting perfectly, as you say. Then on the weekend you changed the setpoint to 40C - on all the weekend days it seems like the AC is allowing the temperature to swing unless it gets to 40C, in which case the AC turns on.
Are you saying you wouldn't have expected it to get that hot on a weekend? If that's the case then you might want to check some of your internal gains, because if you have lights, plug loads, and people set to be on during the weekend without AC, I don't think it's unreasonable for the temperature to get that hot.
If you agree with that and simply want to force the AC to be off on the weekends, there are two ways to do it. The first would be to just change your weekends setpoint of 40C to something ridiculously high (like 200C). Another (arguably more correct) way is to define an availability schedule set to 1 during the weekdays and 0 during the weekends. If you then give that schedule to your cooling system, it will simply ignore whatever setpoint you have told it and stay turned off.
It seems the zone air temperature will reach 40C on weekend, which is not same as my thought.
I tried to change the control type to always 2, cooling only. the problem still there （40C on weekend）.
I tried set 30C cooling sch on weekend, the result become 30C.
why is it happen? 
