most probably radiator fan..
while at it, u might want to changed thermostat as well..
unchanged thermostat will get jammed n cause overheat also..

removing the thermostat is not the cure. u will have slow warm-up time and the water will just flow freely, limiting its time to absorb heat from engine.
if u notice, the thermostat will have small opening when open-up, this will create some pressure before the thermostat. so the water have some time to collect heat from engine.

if want to remove thermostat, remove the center spring and disc leaving the outer disc only.
so u will have the outer disc and install back.

if have done this on my previous ride (turbo engine), result are better.

hope u understand. doesnt have my thermostat pic anymore.

if OFF AC, the fan should spin when temperature rises above normal temp, and stop after temp back to normal. the process goes on and on.

with AC ON, fan start spinning right away until AC achieve its temp set point, and stop, then back ON again when temp rises (its ON together with compressor).

looks like ur fan motor is getting weak.
the fan should produce very loud sound when spinning.
try compare ur fan sound with other proton car (preferably with same model or with single fan)

other thing to check if ur head gasket blown or not.

remove the radiator cap, start engine, let it idle until fully warm up.

if u noticed teh tarik bubble at radiator filling point, most probably head gasket blown.

or check dipstick if got water+oil contamination. usually creamy/choc colour.

what car?
maybe ecu cut off AC when running hi-speed / high rpm, to protect compressor?

the cheapest troubleshoot, try sending the radiator for service. might be clogged.
or if u can get other 2nd hand cheap radiator replaced.
other than that, might be the fan motor weak already. try compare side by side with another car.