Final answer:
Moisture is removed from a system by using a filter drier, which contains desiccants to absorb moisture and ensure efficient operation of HVAC systems.
Step-by-step explanation:
Moisture is removed from a system by using a filter drier. A filter drier is a component in HVAC systems designed to absorb moisture and filter out debris. Moisture in the system can cause issues like ice blockages or corrosion.
Other methods mentioned, such as purging the condenser, draining the oil separator, or reducing water flow to the condenser, do not primarily serve the purpose of removing moisture from the system. The filter drier, however, contains desiccants which actively absorb moisture from the refrigerant, ensuring that the system operates efficiently and effectively.