This Halacha is an excerpt from our Sefer
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A fridge, and its various compartments, does not require Kashering [i.e. Hagala] but simply Hadacha [washing] as it is generally only used for cold foods. [One is to wash the fridge down very well using water and a Chametz killing agent, such as bleach and the like.] However, if one is accustomed to place foods into the fridge even while they are still hot [such as a pot of Chametz soup prior to cooling down] then the custom of all Jewry was to perform Iruiy Keli Rishon.
The elastic insulating side: One must take special care to clean well from Chametz crumbs the elastic insulation that surrounds the doors of the fridge. A suggestive form of cleaning is to use Q-tips dipped in bleach.
The freezer: One is to defrost any ice from the freezer and clean it out.
Covering the shelves: The custom is to cover the shelves of the fridge. This is not required from the letter of the law. [See Halacha 5 in Q&A]
Bedikas Chametz: One is to perform Bedikas Chametz to his fridge prior to entering the Pesach foods back into it, and prior to covering it shelves. [See Chapter 4 Halacha 2!]
Cord: One is to clean the electric cord of the fridge that enters into the outlet.
 Admur 451:58; Nitei Gavriel 76:4
 The reason: As at times the hot Chametz soup spills onto the shelves. [Admur ibid] This is no longer widely practiced today, seemingly due to that we are careful never to place hot foods in a fridge, or due to that anyways we are accustomed to cover the shelves.