.My car ac goes on and off frequently.

Unless you're knowledgeable about vehicle ac systems and operating pressures, second guessing is all you have to go on, Service manuals list operating pressures with some vehicles required to run at a higher rpm with refrigeration gauges connected to monitor and diagnose problems. The sealed ac system is generally not diy friendly as the moment anyone attempts to monitor pressures, that person becomes the ac tech, with or without familiarity of refrigeration. Under normal operations, ac requires the cooling fan to run as the compressor creates hot high pressure refrigerant in the condenser coil in front of the radiator so two radiators need forced airflow otherwise the cooling system may overheat. With ac running, the cooling fan should be running.