I emptied my fridge, took the shelves out, washed everything, and put it back. Two days later it smelled again.
A clean fridge that smells has one of five causes, and none of them are on the shelves you just washed.
1. The Drip Tray Underneath
Every fridge drains its defrost water down a tube into a shallow tray at the back, usually sitting on top of the compressor so the heat evaporates it.
That tray collects water, dust and anything that ran down the back wall. It grows a film and it is the single most common cause of a smell nobody can find, because almost nobody knows it exists.
Unplug the fridge, pull it out, find the tray at the back near the floor, slide it out and wash it with hot soapy water.
2. The Drain Hole Inside
At the back of the fridge compartment, usually at the bottom of the rear wall, there is a small hole. That is where the defrost water goes in.
It blocks with food debris and then water sits in it and goes sour.
Pour a little hot water with baking soda down it, and clear it with a pipe cleaner or a cotton swab if it is not draining.
3. The Door Seal
The rubber gasket has folds in it and those folds collect spills, crumbs and moisture. It is dark, it is damp, and it is right at nose height when you open the door.
Pull the fold open with your finger and wipe inside it with hot soapy water and a cloth. Most people have never cleaned in there.
While you are there, check the seal still seals — close the door on a sheet of paper and pull. If it slides out easily the seal is loose, which means humidity, which means smell.
4. The Plastic Has Absorbed It
Fridge liners are plastic, and plastic absorbs the oils that carry smell. A fridge that held a leaking fish package can smell of it long after the fish and the liquid are gone.
Wipe the walls with a solution of baking soda in warm water, leave it on ten minutes, then wipe off. Repeat if needed.
For a stubborn case, put a bowl of dry coffee grounds or fresh activated charcoal inside for two or three days with the fridge running. Charcoal works better than baking soda and much faster.
5. Something Is Still In There
Check the back of the top shelf, the vegetable drawer liner, and under the drawers themselves — a piece of onion skin or a leaked bag of spinach sits under the drawer where you cannot see it.
Take the drawers right out and look at the floor of the compartment.
Keeping It Fresh
An open box of baking soda does almost nothing. It is not useless but it is very slow and it needs replacing monthly, which nobody does.
Activated charcoal is far more effective and lasts a few months.
Cover everything. Uncovered food both gives off smell and absorbs it — which is also why the butter tastes like the leftovers.
