National Clean Out Your Refrigerator Day was created in 1999.   Discussions on the internet suggest the date was November 10th...then April; until finally the date was settled as the third Wednesday in November thus giving a week prior to the set-in-stone designation of the fourth Thursday as Thanksgiving. 

Whirlpool Home Appliances home economists encouraged people to clean their refrigerators in preparation for upcoming holidays. There was a toll-free hotline enabling people to ask for tips on cleaning their refrigerator. 

The Whirlpool Home Appliance website continues to maintain the "how to clean a refrigerator" information within their blog and a video.    

Tips include:

• It is recommended you clean and maintain your fridge every three months.
• Wiping down shelves, drawers and interior walls can help eliminate fridge odors and stains. It also helps clear away mold spores or bacteria that can spoil food. 
• Avoid bleach & abrasive cleaners
• How to clean mold from a fridge
• Preventing freezer burn
• How to organize