You obviously have a problem with your ac unit which cannot be dianosed here.
First place to look is the thermostat
Because of the thermostat. This will turn on the unit when the temperature gets below what ever degree it is set at and then will turn off when the thermostat gets at that temperature.
Your a/c unit uses different relays(switches) that are energized when the thermostat calls for A/C.
you can simply select "off" on the thermostat to stop operation; however, if you are going to service the ac, the main power cut-off will be within arms reach of the condenser usually located outside .
a bad thermostat or miswire of the low voltage wiring or a bad heating relay stuck in the heating mode.
A central air conditioning unit will commonly turn on and off intermittently. To stop this, adjust the temperature on the thermostat or switch the unit either on or off rather than the automatic setting on the thermostat.
That's the entire point of an AC unit. it's to keep your house at a steady temperature
The ac pump may be seized up.
Most thrmostats have a = or + of degrees that it will turn on or off. For example, if it has a +- 2degrees, it means that if you set it for 75 dgrees, it could be off (or on)at 73 or 77 degrees. Most of them lose their calibration after awhile and needs replacing,
Why does your ac and heater fan turn off and on
The temperature in the air gets cool enough, so its thermostat turns the AC off. When it warms enough, the thermostat turns it back on.
Well you have to press the button that says off to be able to turn it off.