It's best too as I tryed storing a fridge with the door closed and despite all the cleaning fluid and everything i did to it inside to make it spotless it still managed to grow mold and when after a few months I opened it it was green and blue with mold and stunk to high heven that I had to spend hours cleaning it all over again and this time I left the door open and it kept clean. I think it's best to have a flow of fresh air than to be air tight whilst unplugged and in storage.Like these cleaning fluids say they only kill 99% of all germs so obviously the 1% was trapped inside with no escape so where else can it grow! If it had a way out it would of left the fridge and grown someplace better than next to the cleaning fluid.