Relay Switch

Your air conditioner’s relay is merely a switch that turns your HVAC equipment on and off. The reason why we need a relay switch with your air conditioner is that the thermostat operates on 24-volt power and it needs a mechanism to translate an open and close circuit to a higher voltage piece of equipment. The relay allows the thermostat to control the HVAC system with coils that are energized the contactor with the right voltage.