A cooling apparatus for an electronics rack is provided which includes a door assembly coupled to the electronics rack at an inlet or air outlet side of the rack. The door assembly includes: an airflow opening configured to facilitate ingress or egress of airflow through the electronics rack with the door assembly mounted to the rack; an air-to-coolant heat exchanger disposed so that airflow through the airflow opening passes across the air-to-coolant heat exchanger, the air-to-coolant heat exchanger being configured to extract heat from the airflow passing thereacross; and a vapor condenser configured to facilitate condensing of dielectric fluid vapor egressing from at least one immersion-cooled electronic component section of the electronics rack. The cooling apparatus, including the door assembly, facilitates air-cooling and immersion-cooling of different electronic components of the electronics rack.