TSB: Some 2016 ? 2018 model year RX 350 and RX 450h vehicles may exhibit decreased front windshield defroster performance at extremely low ambient temperatures. This condition may be the result of the fresh/recirculation servo actuator separating from the servo, causing the HVAC system to become stuck in recirculation. This condition does not affect the airflow of the defroster. Follow the Repair Procedure in this bulletin to address this condition.