Do you know what is AC contactor?A contactor is an electrical relay that controls the flow of electricity to components in the AC unit. The contactor sends voltage to the condenser and outdoor fan motor. Voltage from the thermostat is sent to the contactor and is registered by the contactor's side terminals.
When a relay is used to switch a large amount of electrical power through its contacts, it is designated by a special name: contactor. Contactors typically have multiple contacts, and those contacts are usually (but not always) normally-open, so that power to the load is shut off when the coil is de-energized.