Why dose my Ac cut off when ever it wants

There are several reasons for random ac cutoff; incorrect diy refilling, cooling fan(s) inoperative, debris blocking airflow thru the front ac condenser coil in front of the radiator, loose drive belt, loss of original refrigerant if this vehicle never required service or repair. Vehicle ac repairs is not diy friendly despite auto stores selling refill kits. If this vehicle was refilled, it may have sealer that increases problems besides possible under or over filling the system. Despite sealer use, damage can still leak refrigerant which is detected, resulting in either intermittent operation or shutdown at any time. A pressure sensor monitors operating pressures and overfilling can result in higher than normal pressures, too dangerous to operate with the sensor sending a disable signal to the engine computer to disable power to the compressor. The same sensor detecting a leak or loss of refrigerant will send the same disable signal to halt compressor operation. Refrigerant moves lubricating oil throughout a system, returning as a mist to the input side of compressors for continuous lubrication. Loss of refrigerant means loss of lube so the sensor detects the loss and disables compressor operation to prevent self destruction without oil returning to the compressor.