It is highly unlikely for an air conditioner (AC) unit to change its switch position from "automatic" to "on" by itself. AC units typically operate based on the settings programmed into the thermostat, and they do not have the capability to change their switch positions independently.
If you are consistently finding the switch moved from "automatic" to "on" when you go back to check, there could be a few possible explanations:
Human error: It's possible that someone else in the household or even yourself accidentally switched the unit from "automatic" to "on" without realizing it. Double-check to ensure that you or someone else is not inadvertently changing the switch position.
Mechanical issue: There may be a mechanical issue with the switch itself, causing it to move from "automatic" to "on" spontaneously. This could be due to loose connections or a faulty switch mechanism. In such cases, it is advisable to contact a professional technician to inspect and repair the unit.
Electrical issues: In rare cases, electrical problems or power surges could cause the switch position to change. This is less likely, but it's worth considering if you experience frequent power fluctuations or issues with other electrical appliances in your home. An electrician can help diagnose and resolve any electrical problems.
If you are consistently experiencing this issue and none of the above explanations seem to apply, it may be worthwhile to consult with an HVAC technician who can assess your AC unit and investigate the issue further. They will have the expertise to identify any underlying problems and provide appropriate solutions.