Window type air conditioner temperature issue

Hi,
My bedroom's air conditioner suddenly started behaving odd out of the blue. The unit is some no-name Chinese 0.6HP unit, but it's just 1 year old and served me well, and it's still cooling well but the problem is that the cooling/resting cycles are too long.
It uses a physical dial to set the desired thermostat temprture, and until now i always kept it at "5", which is the midle of the scale, but suddenly it will only start cooling once iset it to at least "6" on the thermostat scale.
In addittion to that, the cooling cycle is now very long, in which it cools my room very well, actually feels like it cools it more than it should (maybe because i suddenly need to crank up the thermostat more?) and afterwards the "resting" period is also very long in which my room's temperature raises considerably, and this large difference in tempratures during the whole cycle is literally making me sick, i wake up dehydrated and dizzy.

I have successfully replaced the thermostat, but to my surprise, the cooling behaviour havent changed.

So we have an air conditioner that obviously have the ability to cool, but suddenly "forgot" when to start and stop and how much to cool and when to start cooling again, and the thermostat was not the problem, does anyone know what can the problem be?

I hope my explanaion is clear English is not my native language, I highly appriciate any reply
Thank you

 

it's done for I had a "Sunbeam" branded one do this well I took the front off as curiosity got the better of me well it had a refrigerant leak! It was icing up and the ice caused the short on long off cycles as it took a while to melt and get back to normal "temps" for the thermostat bulb to reactivate the contacts thus starting the compressor.