From the Makers’ Guides

An undercounter ice machine that leaks, rattles or stops.

Water dripping inside an undercounter ice machine, a steady run of noise and ice that melts in the bin are all normal, by the makers’ own account. Water on the floor, cubes that stay thin after a cleaning and a bin that empties without the machine starting again are not. The difference comes from how these machines work: they freeze running water on a cold surface, the bin is not refrigerated, and whatever melts or is rinsed off has to leave through a drain.

This page is about the stand-alone machine under the counter: Sub-Zero’s UC-15I and its pump and outdoor versions, GE Monogram’s ZDIS150 and ZDIC150, and Viking’s FGIM515, FPIM515 and FIUI5152D. Each statement names the maker it belongs to. The ice maker inside a Sub-Zero freezer is a different machine.

On This Page

  1. How a clear-ice machine makes ice
  2. Water inside, or a leak
  3. Thin, hollow, small or clumped ice
  4. Which noises are normal
  5. The clean light and the flashing lights
  6. A full bin and no restart
  7. Symptom by symptom
  8. Where our work stops
  9. Questions
  10. Sources

How does a clear-ice machine make its ice?

Two designs are in play, and the makers describe both plainly. In a Monogram ZDIS150 or ZDIC150, water is circulated constantly over a freezing plate. As it freezes the minerals are rejected, which leaves a clear sheet of ice. At the set thickness the sheet is released onto a cutter grid, which divides it into cubes, and the water holding the rejected minerals is drained after each freezing cycle. Viking’s FIUI5152D manual names the same parts: an evaporator plate, an ice slab and a grid cutter.

Sub-Zero’s UC-15I works upside down. Its guide says the water pump sprays water into inverted cups, where it freezes layer by layer until a cube has formed in each. The evaporator is then warmed so that the cubes release and drop into the bin. Sub-Zero puts one batch at approximately 30 minutes, depending on the room and the water temperature. Viking’s FGIM515 and FPIM515 make 24 cubes to a batch, and their manual says the first ice falls after about half an hour.

Two things follow for every one of them. The bin is not refrigerated: Sub-Zero says so in those words, GE says some melting occurs and that the amount varies with room temperature, and Viking’s FIUI5152D manual says the melting is by design, to preserve the quality and clarity of the ice. And the machine needs a drain. GE says the appliance needs a way to drain the water, to a floor drain or through a pump, and Viking’s support page says a drain is required for all of its ice machines. Viking’s FGIM515 manual gives the scale of it: 2 to 4 pints of water enter on each cycle, and 1 to 3.5 pints of that rinse the reservoir and go down the drain.

Published output, by model. Sub-Zero gives the UC-15I(P) up to 50 pounds of ice a day and up to 25 pounds stored, with 12 to 24 hours to refill an empty bin. GE’s service guide gives the 15-inch ZDIS150 up to 50 pounds a day and about 25 pounds stored. Viking’s FIUI5152D manual gives up to 39 pounds in 24 hours at a 72°F room and 55°F water, and its FGIM515 manual counts in hours: 8 to 10 of continuous running to fill the bin.

Is Water Inside the Machine Normal, and What Counts as a Leak?

Inside the cabinet, wet is the working state. Sub-Zero says it is normal for water to spray, drip and leak out of the ice maker assembly during operation, for droplets to fall from all interior surfaces of a UC-15I, and for cubes to melt in the bin. GE says water dripping from the cutter grid into the bin during harvest is normal. Water outside the cabinet is the leak, and these are the makers’ checks for it.

  1. 01

    Shut the water off

    Sub-Zero’s first step for water leaving the unit is the shut-off valve on the supply line. Its answers name an adjacent cabinet and a lower level of the house among the places to look.

  2. 02

    The filter, on a UC-15I

    Sub-Zero asks you to make sure the water filter is securely installed. Its filter answer starts with the power turned off. The cartridge is on the bottom-left side once the door is open and comes out with a quarter turn counterclockwise; a new one goes in the opposite way, with its blue cap taken off first.

  3. 03

    The drain line

    Sub-Zero: properly installed, not blocked, not kinked or looped. A gravity drain on a UC-15I or UC-15IO needs a hose pitched down from the outlet, a quarter inch of fall for each foot of level run. GE adds a machine that was moved, so that its drain tube no longer meets the standpipe, and a clogged household drain. Viking’s FIUI5152D manual adds debris over the bin drain, at the right rear corner of the bin.

  4. 04

    The drain pump

    The UC-15IP and UC-15IPO pump the water up to a drain: 12 feet of rise at most, 100 of run. Sub-Zero’s guide says an open drain pump safety switch stops the machine, and asks that the drain line be checked for kinks before service is called. A Monogram with the pump cuts its own power when water reaches an overfill contact, which GE’s service guide traces to a slow or blocked drain or a blocked vent hose. The pump on a Viking FIUI5152D has to sit level with its vent line clear, lifting no more than 8 feet and running no more than 20.

  5. 05

    The drain cap, on a Monogram or a Viking FIUI5152D

    Both have a cap or plug on the water reservoir. GE says a cap that is not tight lets water leak from the reservoir, and the ice goes thin or stops. Viking’s FIUI5152D manual asks that the drain plug be fully seated. Monogram’s manual and Viking’s FIUI5152D manual each name a whooshing sound as a reason to check it.

  6. 06

    Level, hoses, and whose job it is

    GE asks whether the machine is level and whether a supply or drain hose is damaged. Sub-Zero sends a substantial leak on a new installation back to the installer or to Factory Certified Service, and a leak at the plumbing connections to a plumber. Viking draws the same line: plumbing problems outside the ice machine are for a qualified plumber, not the service technician.

Sub-Zero’s start-up procedure has a drain test in it: a gallon of cold water poured into the bin should be gone within 60 seconds, and if it is not, the drain tube is kinked or the drain was installed incorrectly. For water standing in the machine its answer is the same drain line, then a cleaning. Water under a built-in refrigerator is judged by a different measure.

Why Is the Ice Thin, Hollow, Small or Clumped?

The makers’ lists run through the water arriving, the scale it leaves, the room, and ice that has sat in the bin; the last two rows are a loose cap and the one adjustment an owner is given. Where a cell says a point is not raised, the documents read for that maker are silent on it.

Sub-Zero UC-15IMonogram ZDIS150, ZDIC150 and GEViking FGIM515, FPIM515, FIUI5152D
Water supply and pressure20 to 100 psi in the use and care guide’s troubleshooting table, 20 to 80 psi in the installation guide. Pour a cup of water behind the ice maker curtain: if the spray changes, the pressure is too low20 to 80 psi in GE’s article for its stand-alone ice makers; 20 to 120 psig in the ZDIS150 service guideFIUI5152D: a closed valve, a kinked supply line or low pressure, and filters checked for restriction
Reverse osmosisMay not supply adequate, constant pressure; a booster or regulator, through the RO provider or a plumberAcceptable if the water’s conductivity is no less than 10 microsiemens per centimeter; deionized water is not recommendedNot raised in the two manuals
ScaleMineral buildup blocks the spray nozzles. For shallow, incomplete or white cubes: clean and sanitize, replace the filter, see to a water softener that is not working, have the water testedScale keeps the sheet from releasing from the freezing plate, and cloudy ice is its usual sign. GE’s article says to clean as often as every 6 monthsFGIM515: minerals left in the machine cause malformed cubes, and an acid cleaning dissolves them. FIUI5152D: a slab that will not release means cleaning the evaporator
The room50°F to 100°F indoors, to 110°F for the outdoor models. Heat and direct sun melt the ice quickly55°F to 100°F for the ZDIS150; above 90°F production fallsFIUI5152D: no colder than 55°F, and under 90°F built in or 100°F freestanding
ClumpsNot raised; Sub-Zero says only that cubes melting in the bin are normalThe bin is not refrigerated, so ice not used regularly melts and clumps; a room under 55°F does it too. Break the clumps with the scoopFIUI5152D: the same cause and the same scoop. Cubes that run large or small when little ice is used are normal
The drain capNot raisedNot tight: thin ice or noneFIUI5152D: plug not seated, little or no ice
An owner’s adjustmentCube finishing time: up to five extra minutes of freeze, one minute at a timeNone in the owner’s manual. Thin, normal and thick appear in the service test modeNone; both manuals say no adjustments are needed

The cleaning is each maker’s own. Sub-Zero’s runs from the CLEAN key with its own cleaner and sanitizer, and it wants a Sub-Zero filter in the machine: third-party filters, it says, have not been tested. Monogram’s takes the whole 16-ounce bottle of Nickel Safe Ice Machine Cleaner and about 70 minutes. Viking’s FGIM515 takes 8 ounces of its scale remover and two half-hours, at least once a year and preferably twice; the FIUI5152D manual says every six months. What Phoenix-area water does to that interval, city by city · Chandler’s water and its ice machines.

Sub-Zero’s cube adjustment is made from the machine’s own POWER and CLEAN keys. On a Monogram, a slab that stays thin, partial or irregular with the reservoir full is on the service guide’s list, not the owner’s: a hot gas valve, a seeping water valve, a blocked condenser or stalled fan, the recirculation pump, a partly blocked water distributor, or a refrigerant leak or restriction.

Which Ice Machine Noises Are Normal?

An ice machine does not sound like a refrigerator, and Viking’s manual says so before it lists the sounds. Sub-Zero’s sentence is the shortest: the UC-15I is noisy in general, as it continuously produces ice.

The soundWhat the maker says it isNormal?
Running noise through the daySub-Zero: the UC-15I(P) makes ice continuously. It needs airflow, so the kickplate is not to be coveredYes
Fan and water pump while freezingGE and Viking: the fan moving air and the pump circulating water. Monogram: the pump runs for the entire cycle, and water is added once in eachYes
A bang, a thud, clicks at harvestMonogram: the slab dropping off the plate and ice falling into an empty bin. Viking FIUI5152D: a thud as the slab slides onto the grid cutter, clicks as the cubes landYes
Buzzing, rattling, splashing, gurgling, a click or chirpViking FIUI5152D: the water valve opening to fill the reservoir, water in the supply line, water running over the evaporator plate, refrigerant flowing. Monogram: the compressor may click or chirp as it restartsYes
A drain pump, even with the machine offSub-Zero: a pump model is noisier than a gravity drain, and the pump runs with the unit turned off as long as the house power is onYes
WhooshingMonogram: check that the water supply is on and the drain cap is tight. Viking FIUI5152D: water not reaching the machine, or the drain plug not fully seatedNo: an owner’s check
Grinding, a cavitating pump, ice that sticksGE: minerals on the freezing plate stop it releasing new ice. Its service guide ties grinding to an empty reservoir with a slab partly released or catching on the cutter grid, or, with the reservoir full, to the recirculation pump. Viking: a slab caught between the plate and the grid cutter means checking the level, then a cleaning cycleNo: level and cleaning, then service

For a machine that is only loud at the wrong hour, Viking’s FGIM515 manual suggests an appliance-grade timer on the power supply, and a UC-15I has a DELAY key that holds off ice making for two, four or eight hours. Sub-Zero’s line for anything else is that an unusual noise its steps do not cure needs service. Which refrigerator noises the makers call normal.

What Does a Clean Light or a Flashing Light Mean?

It depends on the machine. On a Sub-Zero UC-15I the CLEAN light is not a reminder at all; on a Monogram and a Viking it is. None of the control panel pages read for this guide shows a light labeled Service.

MachineLightWhat the guide saysWhat to do
Sub-Zero UC-15ICLEAN, greenLit only in a cleaning cycle someone started. Three minutes in it flashes for one minute, the moment to add cleaner or sanitizer, then stays steady and goes out at the endLet it finish: Sub-Zero says a started cycle cannot be canceled, and cleaning plus sanitizing take over an hour
Sub-Zero UC-15IREPLACE FILTER, redComes on after 8,000 freeze and harvest cyclesA new filter, then CLEAN held for six seconds to reset; discard the first batch of ice
Sub-Zero UC-15IICE, blue, flashingAutomatic shut-off: two maximum freeze and harvest cycles in a row, 55 minutes each, or 120 cycles without filling the bin, about two daysWater on, then an hour; then the filter out; then Factory Certified Service
Sub-Zero UC-15IThe 2, 4 or 8 hour lightA delay is running, and no ice is made until it endsA fourth press of DELAY cancels it
Monogram ZDIS150CLEAN, yellowThe control senses that cleaning is approaching: after 50 hung slabs or 3,500 freeze cyclesBuy the cleaner
Monogram ZDIS150CLEAN, redAfter 70 hung slabs or 4,000 freeze cycles. Left alone, ice production decreases significantly or stopsClean: CLEAN held 3 seconds, blinking for about 70 minutes, solid when complete
Monogram ZDIS150OFF, flashing in twos or threesTwo blinks: the bin thermistor open or disconnected. Three: a harvest that did not completeService
Viking FGIM515, FPIM515Time to Clean; Check Water, flashing blueTime to Clean comes on after 6 months of use and stays on until the ice making system is cleaned. Check Water: the control checks every 20 minutes and restarts ice making by itselfClean; check the supply
Viking FIUI5152DCL alternating with ICE in the displayA reminder every 3,000 cycles. Normal ice production continues, and it clears when a cleaning cycle completesClean; the manual’s interval is six months

A hung slab, in GE’s service guide, is a harvest that begins less than five minutes after the freeze did. The same guide calls the first Monogram color yellow on one page and amber on another. On a UC-15I a steady blue ICE light means only that the machine is making ice, and it is off during a cleaning cycle. The REPLACE FILTER count belongs to the ice machine alone. A Sub-Zero refrigerator’s filters run on triggers of their own.

Why does it fill the bin and not start again?

Each machine stops on a cold sensor in the bin. On a UC-15I it is the bin thermostat, a covered metal rod at the inside left front of the bin, with a clip that hangs about an inch down. Ice touching the clip cools it and production stops; when the ice no longer touches, the clip warms and production resumes. A Monogram ZDIS150 reads a bin thermistor, and treats the bin as full while that reads below 36°F. On a Viking FGIM515 the sensor is the loop of tubing on the right that also holds the scoop.

Sub-Zero publishes a test. Lay three ice cubes on the clip for about five minutes and production should stop; take them away and it should restart about five minutes later. If the machine stops before the bin is full, or keeps going after, Sub-Zero’s first suspicion is the room, too warm or too cold. Its guide describes an ice level control behind the kickplate, and warns that the power stays on there, beside a fan blade and electrical connections. That warning is reason enough to leave the control to service, which is also where Sub-Zero sends a machine the adjustment does not cure.

A cold room can do the same thing without a fault. Monogram’s manual says the room must be above 55°F, or the bin thermostat may shut the machine off before the bin is full, and it may not restart. Viking’s FIUI5152D manual says the same at the same 55°F. Sub-Zero’s band for the UC-15I begins at 50°F. The room temperatures the makers publish for a garage or an outdoor kitchen.

Then come the stops that look like a full bin and are not. On a UC-15I, a lit 2, 4 or 8 hour light is a delay someone set; a flashing blue ICE light is the automatic shut-off in the table above; and on a pump model an open drain pump safety switch keeps the machine off. On a Monogram, the cleaning cycle ends with the machine off, and ON has to be pressed to resume. On a Viking FIUI5152D, the drain pump can shut the machine off for a time when excess water builds up. The manual says to wait a few minutes, and if water remains in the bin, to check the pump’s vent line and the drain line for obstructions or kinks.

Symptom by Symptom: What to Check, and Who Fixes It

The third column lists the causes the makers’ documents name, which is not a verdict on your machine. Where the last column says service, read the maker’s own network while its warranty runs, and an independent company such as ours once it has ended.

What you noticeCheck first, yourselfWhat the makers point toWho fixes it
Drops and spray inside; cubes melting in the binNothingNormal operation, in Sub-Zero’s and GE’s wordsNo one
Water on the floorSupply valve off; filter seated; drain line for kinks; drain cap tightThe drain line or pump, a loose cap, a hose or a connectionYou for the cap and filter; a plumber for house plumbing; service for the machine
Water standing in the binDrain line not kinked or looped; nothing over the bin drainA restricted drain, or a drain pump that is slow or defectiveA plumber for the drain; service for the pump
Thin, hollow, shallow or incomplete cubesWater pressure; the filter; a full cleaning; the drain capLow pressure, scale, a clogged filter; on a Monogram, also the service guide’s valves, pump, fan and refrigerantYou first, then service
Clumps in the binBreak them with the scoop; a room above 55°FAn unrefrigerated bin, and ice not usedNo one
Slow to fill in summerKickplate or grille clear; the room’s temperature; direct sunHeat. GE says production falls above 90°F, and Sub-Zero says heat and direct sun melt the ice in the bin quicklyYou
Blue ICE light flashing on a UC-15IWater on; wait an hour; take the filter outThe automatic shut-off, after cycles that ran to the maximum or never filled the binService, if it does not restart
The bin was emptied and nothing restartsDelay lights; a cold room; ON after a cleaning; three cubes on the clipThe bin thermostat or thermistor, or a drain pump cut-outYou for settings; service for the sensor
A new whooshing or grindingWater supply on; drain cap tight; machine levelAn empty reservoir, a stuck slab, the recirculation pumpCleaning, then service

Sub-Zero repair in the Phoenix metro · Viking repair · Monogram repair.

Where our work stops.

Most of this page is yours, and costs nothing: the supply valve, the filter, the scoop, the cleaning, a drain cap, the room the machine stands in. Sub-Zero’s guide adds one task it recommends for its own network, an annual cleaning with the machine taken apart. The drain beyond the cabinet and the supply line behind it go to a plumber, as Sub-Zero and Viking both say, and the voltage at the wall is an electrician’s. Inside the maker’s warranty the call goes to the maker first. What each maker’s warranty covers, and for how long.

What we repair is the appliance itself. Aphelion Appliance Repair is an independent company that repairs Sub-Zero, Viking and GE Monogram ice makers and ice machines at home in the Phoenix metro: ice maker faults, control board and sensor errors, and sealed-system faults. What we service on ice makers.

The diagnostic visit is $119 for the first appliance and $69 for each additional appliance on the same visit, both waived if you go ahead with the repair. The repair is one fixed price, with labor and genuine OEM parts on separate lines, approved before work begins and never hourly. On Sub-Zero, Wolf, Viking and Monogram, a repair made with the genuine parts we supply carries our 12-month warranty on parts and labor. A part that has to be ordered usually reaches us within a week. Some arrive sooner, and now and then one takes longer. The day it arrives we call you, and you choose the time for the repair. What happens on the visit.

Questions

Is it normal for water to drip inside an undercounter ice maker?

Yes. Sub-Zero says it is normal for water to spray, drip and leak out of the ice maker assembly of a UC-15I during operation, and for ice cubes to melt in the bin, which is not refrigerated. GE says water dripping from the cutter grid into the bin during harvest is normal on its stand-alone ice makers. Water outside the cabinet is different: Sub-Zero’s steps are the supply valve off, the filter checked, the drain line checked, then service.

Why is my undercounter ice machine making thin or hollow ice?

The makers’ lists start with water and scale. Sub-Zero’s use and care guide asks for 20 to 100 psi at a UC-15I and its installation guide for 20 to 80 psi. Sub-Zero also gives a test: pour a cup of water behind the ice maker curtain, and if the spray changes, the pressure is too low. The use and care guide answers shallow, incomplete or white cubes with a cleaning and a new filter. On a Monogram ZDIS150, GE says a drain cap that is not tight leaks water and causes thin ice or no ice. Viking’s FGIM515 manual says minerals left in the machine cause malformed cubes, and calls for an acid cleaning with its scale remover.

What does the clean light mean on a Sub-Zero ice maker?

On a UC-15I it means a cleaning cycle is running, not that one is due. Sub-Zero says the green CLEAN light flashes during the cycle to show when to add cleaner or sanitizer: three minutes in, for one minute. It then stays steady and goes out when the cycle is complete. Sub-Zero’s cleaning answer adds that a started cycle cannot be canceled and that cleaning and sanitizing together take over an hour. The red REPLACE FILTER light is the reminder; it comes on after 8,000 freeze and harvest cycles and is reset by holding CLEAN for six seconds.

Why does my ice maker fill the bin and then not start again?

First rule out a setting. On a Sub-Zero UC-15I, a lit 2, 4 or 8 hour light is a delay, and a flashing blue ICE light is an automatic shut-off that Sub-Zero answers with the water supply, an hour’s wait and the filter taken out. A cold room is next: Monogram’s manual and Viking’s FIUI5152D manual both say that below 55°F the bin sensor may shut the machine off and it may not restart. After those, the makers’ documents point to the bin thermostat on a Sub-Zero and the bin thermistor on a Monogram.

Is a noisy undercounter ice machine normal?

Largely, yes. Sub-Zero says the UC-15I is noisy in general as it continuously produces ice, and that a model with a drain pump is noisier than one with a gravity drain. GE and Viking list the fan, the water pump and ice falling into the bin as normal, and Viking’s FIUI5152D manual adds buzzing, rattling, splashing and a thud at harvest. A whooshing sound is the exception that Monogram’s manual and Viking’s FIUI5152D manual both name: check that the water is on and the drain cap or plug is tight.

Sources

  1. Sub-Zero (Sub-Zero Group), owner support answers, checked October 7, 2026: Undercounter Ice Maker UC-15I Troubleshooting; Undercounter Ice Maker Troubleshooting (315I); Undercounter Ice Maker Leaking Water; UC-15I Water Dripping from Unit Ceiling; UC-15I Noise; UC-15I Making Too Much Ice and Bin Thermostat; UC-15I Not Running with Ice Indicator Flashing; UC-15I Delay Function.
  2. Sub-Zero, further answers on the UC-15I, checked the same day: Water Filter; Cleaning Instructions; Cleaning Tips; First Time Start Up Procedure; Water Flow and Usage; Ice Production and Capacity; Ice Cube Size, Shape and Weight; Gravity Drain or Pump Selection Considerations; Drain Pump Considerations.
  3. Sub-Zero Undercounter Ice Machine Use & Care Guide, 7023607 REV-A 8/2011, for models UC-15I, UC-15IP, UC-15IO and UC-15IPO: models and features (p. 4), control panel and lights (p. 5), ice making operation and automatic shut-off (p. 6), bin thermostat (p. 7), cube weight and cleaning (pp. 8 and 9), water filter (p. 11), troubleshooting guide (p. 12).
  4. Sub-Zero Undercounter Ice Machine Installation Guide, REV-C 8/2016, headed UC-15I(P)O in the copy read: plumbing, with the water supply, its pressure and the gravity drain (p. 6).
  5. GE Monogram Automatic Icemaker Owner’s Manual, ZDIC150 and ZDIS150, two editions read as text: 49-60727 (08-14), Problem Solver (p. 14), for the whooshing sound and the loose drain cap; and 49-60692 (06-13), for the 16-ounce bottle of cleaner, the room above 55°F and the bin shut-off, and the loose drain cap. Both editions give the 90°F limit on ice production.
  6. GE Appliances Technical Service Guide, Monogram Under-the-Counter Icemaker, models ZDIS150WSS, ZDIS150WBB and ZDIS150WWW, Pub. 31-9196 (March 2010): specifications (p. 5), freeze, harvest and clean modes (pp. 9 and 10), care and cleaning (p. 13), control board diagnostics (pp. 35 and 36), troubleshooting (pp. 38 and 39), service test mode (p. 40).
  7. GE Appliances, support articles for its stand-alone ice makers: Monogram Ice Maker, How It Operates; Ice Maker, Leaking; Ice Maker, Normal Noise; Standalone Ice Maker Noise; Ice Maker, Cubes Clumping; Ice Maker, Cubes Cloudy; Ice Maker, Incoming Water Requirements.
  8. Viking Use & Care manual, 15-inch Undercounter/Freestanding Ice Machine, models FGIM515, CFGIM515, FPIM515 and CFPIM515, F20733C EN (040116): start-up, use and noise (p. 4), water quality (p. 5), scale removal (p. 7), troubleshooting guide (p. 8).
  9. Viking Install, Use & Care Manual, Professional Undercounter Ice Machine FIUI5152D, marked 30740 (110824): operation, ice production and sounds (p. 12), controls (p. 20), clean reminder (p. 22), troubleshooting and the drain pump (pp. 25 and 26). Viking Range, support FAQs: a drain is required for all ice machines.

Written from these sources, each read on (checked again ), and reviewed that day by Aphelion Appliance Repair, Phoenix. The manuals were read as page views in an online manual library, and their page numbers are that library’s; a printed page can differ by one. Lights, limits and procedures belong to the models named beside them, and GE’s support articles cover GE Appliances ice makers in general, not Monogram alone. Nothing here replaces the maker’s own instructions.

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