Prevention is the best cure for any HVAC unit. There are, however, other reasons as to why your AC unit could fail.
It's important to cover your AC unit to ensure that the AC coils remain protected from humidity, dust and even freezing. This could potentially contribute to AC failure.
Poor air flow
When air is blocked by dirt, it can cause issues to the unit and subsequentially cause failure.
A thermostat is an extremely important component of an HVAC unit as it regulates the temperatures. A faulty thermostat can contribute to failure of an AC unit.