What is causing my ac unit and thermostat not to work with one another

Inside unit and thermostat are not working properly. In the beginning, something needed to be changed in it,it was a small black box and a round cylinder like plug thing.changed out the thermostat also.worked for over a year. I kept it clean from dust by cleaning the air filters and the coil unit. One summer I noticed outside unit was freezing up.well, bought cleaner for coils cleaned inside out from leaves and debris.had plugs checked well had it serviced, this was a new outside unit since my boyfriend killed the first one because a snake was going up the side of it. It stopped freezing. Winter started and it started to always run. The heater never turned off, I had to throw the power from the box cause the thermostat wouldn’t turn it off. Changed out thermostat again, makes 2 one so far. Then the next summer it gets crazy, the outside would freeze,service that, then inside unit freeze,serviced that, then it would kickoff fan was always running had to throw power in box cause thermostat wouldn’t turn it off. Changed thermostat s,this makes 3. Now nothing works. All together 4 new thermostats.