When I open or close one of the doors on my LG fridge freezer, why does the other one rattle?
The door can rattle due to the air pressure inside (cool air circulation).
Rattling is a normal phenomenon and not the result of a defect.
Door can rattle if the rubber gasket is dirty, you could try cleaning the
gasket to see if this improves.
※ If you get a continous beeping sound, this could be due to a
defective door sensor and service would be required.