How long can air conditioner be kept on without overheating?

An air conditioning unit is design to work continuosly, they should never overheat unless the condensor is block, or there is a high ambient temp around the condensor.Also if the AC is not design to deal with the size of room you want it to cool it will run continuosly until one of it's safety devices is triggered.The system will shut down and display a flashing fault code. ie (F3---low suction temp)