How to Reset a Sub-Zero Ice Maker After a Fault or Outage

First, confirm the ice maker is actually on

Before resetting anything, read what the panel is telling you. A lone cube icon on a Classic (CL), Designer (DET, DEC) or IW-30CI panel says the ice maker is switched on, while a row of three says Max Ice is engaged, lifting output by as much as 30% for a 24-hour period and letting some components spin faster with a noticeably different sound. No icon at all usually means someone switched the ice maker off, often while washing the bin. Sliding the bin out also triggers a 3-minute delay on CL, DET and DEC units before the ice maker carries on, so an idle mechanism right after you put the bin back is expected; planning to leave the bin out for an extended spell is, by Sub-Zero's advice, a reason to turn the ice maker off first. Sabbath Mode is the quiet one to watch: it turns off the ice maker system and the door alarm, keeps them off, and comes right back after a power failure, so an ice maker parked by a guest or house sitter can look broken when nothing is wrong.

• One cube showing: the ice maker is on, so look at the water supply next.
• Three cubes showing: Max Ice is running for its 24 hours and the extra noise is normal.
• No cube showing: switch the ice maker on and give it a full day before judging output.
• Sabbath Mode set: exit it first, or the ice maker will stay off no matter what you press.

The flashing cube is a flood stop, not a glitch

A single ice cube icon that blinks with no chime on an older Classic built-in unit is a fault code rather than a status light. It tells you the ice maker water valve stayed open longer than it should, so the control disabled the ice maker to keep water from spilling into the freezer and onto the floor. Cycling the ice maker off and on will not clear it. The right order is to find out why the water did not arrive or did not stop, then clear the code by holding the Alarm key until CFC, which stands for Clear Fault Codes, shows on the display. Clear it without fixing the cause and the blinking cube tends to return. The same trouble often explains a puddle under the freezer drawer or a sheet of ice fused across the bin, which is why a search for a Sub-Zero ice maker leaking water so often leads here; our page on water under a refrigerator covers the other places a leak can start.

• The shutoff valve under the sink or behind the unit is turned fully open.
• The supply line behind the refrigerator has not kinked after the unit was slid back in.
• The water filter, on models that have one, is not long overdue or clogged.
• The fill tube into the ice maker is not frozen shut, which can follow a door left ajar.

When the whole refrigerator has lost power

A dark display and no hum mean the ice maker is the least of your worries, and the reset begins at the electrical panel. Locate the breaker that feeds the refrigerator, push it fully off and then back on; a tripped breaker often rests in a middle position that looks on at a glance. When power returns, a healthy Sub-Zero restarts by itself, but the ice maker needs several hours for the freezer and the mold to get cold enough to harvest. During the outage, keep both doors closed. Sub-Zero notes that an empty refrigerator typically takes about 3 hours to rise above 45°F (7°C) in the fresh food section and above 20°F (-6°C) in the freezer, so opening the doors to check on things only shortens that window. Also remember what a power cut does to settings: a unit that was in Sabbath Mode goes straight back into it with the ice maker still off, and the Auto Delay schedule on a UC-15I has to be set again after any outage.

• Breaker reset and the panel lights up: watch the ice maker for a day before calling.
• Breaker trips again right away: leave it off, because that points to a short and not a hiccup.
• Breaker holds but the display stays blank: the control or its power supply has likely failed.

Undercounter ice makers have their own controls

The standalone undercounter ice makers do not share the refrigerator panel, and most of what owners call a reset on them is really a timer or a reminder. On the UC-15I, one tap of DELAY halts ice for 2 hours, a second tap stretches that to 4 and a third to 8, which helps before a party and baffles everyone if someone tapped it and walked away. Auto Delay, which you program while the unit is switched off, repeats every 24 hours. The REPLACE FILTER message glows red after 8000 ice-making cycles, and once a fresh filter is installed you touch and hold the Clean key for 6 seconds to clear it. The UC-15I has no Sabbath Mode, so that is one cause you can cross off. When it hums along yet the bin stays empty, Sub-Zero's checklist is supply pressure somewhere from 20 psi (1.4 bar) up to 80 psi (5.5 bar), plus room air from 50°F to 100°F for the indoor version or 50°F to 110°F for the outdoor version. For the Designer Series Undercounter Ice Maker, the supply should be 115 VAC, 60 Hz on a dedicated 15 amp circuit; a GFCI is discouraged indoors because it can interrupt the unit, yet it is required for an outdoor installation.

• Pressed DELAY three times: expect 8 hours without ice before production resumes on its own.
• REPLACE FILTER lit in red: fit the new filter, then hold Clean for 6 seconds.
• Patio unit gone dark: press the reset on its GFCI outlet before anything else.

Filter reminders that only look like faults

On CL, DET and DEC touch controls, Snooze/Refresh shows up when the water filter or the air purification cartridge is due. It is a reminder and not a breakdown; pressing Snooze puts it off for 24 hours, and after you replace the filter or cartridge its countdown starts over and runs for roughly a year. Swapping a Classic (CL) filter is a short job: lift the grille from its bottom edge, rotate the old filter a quarter turn counterclockwise and draw it out, peel the plastic cap off the new one, slide it in and rotate it clockwise, then follow the prompts on the control panel. Not every Sub-Zero carries a filter at all. Wine storage other than the IW-30CI, the 500 Series, 600 Series and 700 Series, the UC-24 and DEU undercounter refrigeration and the ID drawers have no internal filter, and the DEU1550I ice maker does not come with one, so on those models there is no filter alert to clear and an ice problem lies somewhere else.

Hard water, cleaning and long absences

Because the water here is hard, the minerals that spot shower glass also crust onto an ice maker's valve, mold and lines, which slows the fill and can leave cubes small or hollow. Sub-Zero's schedule for the Designer Series Undercounter Ice Maker is a first cleaning when it goes in, then one every three to six months, sooner the harder your water runs; the reminder ships set at three months, and every cycle calls for 1/2 cup of descaler plus 1/2 tablespoon of sanitizer. With Pacific Beach water, the three-month end of that range is the sensible habit. Second homes need one more routine. Before a long trip with a Classic (CL) or Designer (DET, DEC) unit, Sub-Zero suggests turning it off at the control panel, emptying it and propping the doors slightly open so the inside stays dry, then putting in a new water filter before you start it up again. If the house stands empty for months at a time, our page on maintenance for a house left empty is worth reading before you leave.

When no reset will bring it back

A reset only helps when the hardware is sound. If the breaker holds and the display stays blank, the control board or its power supply has probably failed, and pressing keys will not change that. If the panel lights up and shows one steady cube but the ice maker never fills, the water valve, a frozen fill tube or the ice maker module is the likely suspect. If the freezer feels warmer than usual, the ice maker may be fine and simply waiting for a mold cold enough to release cubes, which points back to airflow, and our guide to evaporator fan diagnosis is the logical next read, since a stalled fan warms the freezer and slows ice well before food starts to soften. Finally, if the blinking cube comes back each time you clear CFC with the water on and the line straight, the valve itself is probably sticking. For any of these, call (858) 947-1121 and describe exactly what the panel shows.

• Blank display with the breaker on: control board or power supply.
• Steady cube but no fill: water valve, frozen tube or the ice maker module.
• Warm freezer and slow ice: airflow, often the evaporator fan.
• Blinking cube that keeps returning: a water valve that sticks open.