In most standard residential or commercial HVAC (Heating, Ventilation, and Air Conditioning) systems, it is not common to have three thermostats controlling a single AC unit. Typically, there is one central thermostat that controls the operation of the entire system.
The central thermostat is responsible for sensing the temperature in the designated area and sending signals to the HVAC system to activate heating or cooling as needed. It communicates with the AC unit to maintain the desired temperature set by the user.
However, there are certain advanced HVAC systems that support zoning. Zoning allows for different areas or zones within a building to have individual temperature control. Each zone has its own thermostat that communicates with dampers in the ductwork, allowing for independent temperature adjustments in each zone.
If you're considering implementing a zoning system or have specific requirements for multiple thermostats controlling a single AC unit, it is best to consult with an HVAC professional. They can assess your specific needs and advise you on the feasibility and appropriate setup for your situation.