The Toe-Kick Is the Lung: Ventilation on Undercounter Units

An undercounter unit has no open back or top to breathe through, so everything it does with heat happens at floor level, behind the grille in its toe-kick. On Mercer Island, where so many of these units went in during remodels finished to the last detail, that grille is the part most often covered, boxed in or simply forgotten.

Where the heat goes

A refrigerator does not make cold. It moves heat out of the cabinet and releases it into the room through the condenser. On Sub-Zero undercounter units that coil sits at the bottom, behind the kickplate, and a fan draws room air in through it. Air has to reach it from the room and warmed air has to leave again, and in a unit set flush into cabinetry the kickplate is the opening you can see and keep clear.

Sub-Zero takes this seriously. Its Designer undercounter guide carries a warning that the ventilation openings must stay unobstructed, both on the appliance and in the built-in structure around it. That warning is worth reading twice before a carpenter finishes a toe-kick, because it covers the built-in structure as much as the machine inside it.

What remodels do to it

• A board carried straight across. Matching the cabinetry, a carpenter runs the toe-kick board across the unit’s grille or sets a solid panel in front of it.
• A runner or mat. Kitchen and bar mats slide under the kickplate and sit against the grille for months.
• Storage in front. Cases of sparkling water, shopping bags, a dog’s bed: anything that lives against the grille for weeks.
• A new floor. Tile or wood laid after the unit went in raises the floor in front of it and narrows the gap below the kickplate.
• Dust with nowhere to go. An open grille that is never cleaned ends up matted, which amounts to the same thing.

None of these stops a unit overnight. They make it run longer and hotter week after week, until it cannot hold its temperature on a warm afternoon and the fan behind the coil begins to wear.

Cleaning what you can reach

Sub-Zero treats condenser cleaning as owner maintenance, with the power off and gloves on. On the current Designer undercounter line the kickplate comes off with two mounting screws and the coil wants cleaning every six to twelve months; on the older UC-24 models the interval is three to six. Homes with shedding pets want it done more often than that. Use a soft brush and a vacuum, and keep to the direction of the fins so they do not fold. Cleaning chemicals are unnecessary; a brush and a vacuum are the whole kit. Everything behind the coil, including the condenser fan, stays with us.

What a starved unit does

The early signs are mild. The air at the grille feels hot, the unit seems to run all the time, and the cabinet sits a degree or two above its set point by late afternoon. On the older UC-24 models SERVICE may flash, which Sub-Zero ties to a temperature problem or a condenser that needs cleaning. In a wine unit the same starvation warms both zones at once, which is why the note on a wine unit warm in both zones also begins at the kickplate.

If the temperature has not come back within a day of clearing the grille and cleaning the coil, that is a service call. That visit is booked as refrigerator repair.

Before you call

1. Step 1

   Kneel down and find the grille

   Check that the unit's own grille is visible, not hidden behind a board or trim cut to match the cabinets.

2. Step 2

   Move whatever rests against it

   Rugs, cases of water, shopping bags, a pet bed. Anything touching the grille goes, and the floor in front stays clear.

3. Step 3

   Feel the air at the grille

   With the unit running, hold a hand near the grille. Warm, moving air is normal; hot, still air suggests a matted coil or a fan that has stopped.

4. Step 4

   Clean the coil if it is due

   Power off at the control panel, gloves on, then brush and vacuum with the fins, not across them. Refit the kickplate before switching back on.

Past these checks the fault is inside the machine. Call Mercer Island Sub-Zero Service on (206) 208-3377 and say which step changed nothing.

Asked about this

Can holes be drilled in a toe-kick board placed over the grille?

That is a cabinetry question, and your cabinetmaker should ask Sub-Zero directly before anything is cut. What we can say from the repairs we do is that a board with a few holes in it is not the same as leaving the unit's own grille open to the room. We diagnose and repair the unit; we do not alter cabinetry.

The unit runs constantly but stays cold. Is that a problem?

Not necessarily. There is no set time a compressor should run: the room, the load and door openings all change it. Constant running in a cool room with a light load deserves a look, though, and a hot grille alongside it points at the condenser. If you want it looked at, ring Mercer Island Sub-Zero Service on (206) 208-3377.