The short answer
A leak from the BBB family is almost always the defrost drain or the water supply, and telling them apart takes one observation: where the water is. On this platform the drain blocks before anything else does, which is why it leads this ranking.
What you observe
- Water pooling under the crisper drawers — The classic blocked defrost drain: melt water has nowhere to go and backs into the cabinet.
- A sheet of ice on the floor of the compartment — Same fault caught later, once the pooled water has frozen.
- A crackle of ice under the drawers before any water appears — The early stage of a blocked drain, caught before the water reaches the floor.
- Water appearing a day or two after the unit was moved — A displaced drain pan or a strained supply connection rather than a drain fault.
- NEAR MISS - condensation on the outside of the doors — That is humidity and seal performance, not a leak.
Causes, most likely first on BBB
- Blocked defrost drain — Ranked first on the BBB family: a tall cabinet has a long drain run with more places to block, and the pooling appears far from the blockage. The order below follows the air path rather than the refrigeration circuit, which is a family property and not a model one. What moves against the brand-generic order is lower down: door seals and condensation sits above drain pan cracked or displaced here, because this family is a single build with fixed access points.
- Water supply connection or line — Second: the supply runs through a built-in housing where it is hard to inspect and easy to pinch.
- Door seals and condensation — Third: a heavy built-in door can drop on its hinges and leave a corner gap that condenses continuously.
- Drain pan cracked or displaced — Fourth: the pan is under the housing and is rarely inspected, so an overflow shows as a floor leak with no visible source.
- Ice maker fill valve or its tubing — Last: last, and the valve sits at the back of the housing where the leak travels before it shows.
Check in this order, and why
- Empty the compartment and find the drain opening — It is the likeliest cause and it is visible once the shelves are out.
- Flush the drain channel with warm water — It confirms the diagnosis and clears most blockages in one step.
- Check whether the wetness is inside the cabinet or behind it — Inside is a drain or a seal; behind is the supply. This splits the fault in one look.
- Test the seals with a sheet of paper around each door — Last, because it explains condensation rather than standing water.
Before you open anything
Safety
Isolate at the breaker before any panel comes off, and leave the sealed system alone entirely: refrigerant work is licensed work and the tools for it are not owner tools.
When to call a technician
Shut the supply at the stop tap the moment a supply-side leak is confirmed. Clearing a drain and testing seals are owner work; a valve, a heater at the drain or a cracked pan is a service call on this family.
Other BBB pages
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
