Empty Containers
WARNING: This page is about a different car, the 2018 Volkswagen Jetta, 2017 Volkswagen Jetta, 2016 Volkswagen Jetta, and 2015 Volkswagen Jetta. However, it is still accessible from the selected car via links, so may be relevant.
Empty refrigerant vessels must always be sealed to prevent the ingress of moisture. Moisture causes steel vessels to corrode. This weakens the vessel walls. In addition, rust particles entering into refrigeration systems from vessels will cause malfunctioning.