Final answer:
The component used to pass line voltage to the air conditioner's condenser fan motor is the contactor, which acts as a relay for engaging power to the motor. Additionally, the condenser is the part that converts refrigerant gas into liquid.
Step-by-step explanation:
The component of an air conditioner's system that is used to pass line voltage to the condenser fan motor is the contactor. The contactor acts as a relay to engage power to the condenser. It receives a control signal when cooling is required and then electrically connects the high voltage line to the motor.
The component that converts the refrigerant gas back into a liquid form within the air conditioning system is the condenser. This process releases heat, which is then expelled from the system.