Sub-Zero · Error codes
Sub-Zero Undercounter Error Codes
A Sub-Zero UC-24 has one fault signal on its face, the SERVICE word, and a short list of numbered codes behind it. The UC-15I ice machine has no code list at all; it tells you what is wrong through the ice it makes, or stops making.
$79 service call, applied to the repair. Monday to Saturday, 8 AM to 7 PM.
In short: on a UC-24, a flashing SERVICE means the compressor ran far longer than it should, and a steady one means codes are stored. Before you call, clear the kickplate grille and check that the door closes on its own. Freezer and defrost codes come only from the UC-24C and UC-24CI combinations. On a UC-15I, the ice itself is the readout. Meanings vary by model and production era.
Which undercounter you have, and what it can report
The tag inside the cabinet tells us whether there is a freezer and a defrost heater, which decides half the code list.
- UC-24R, UC-24RO, UC-24B and UC-24BG: refrigerator, outdoor refrigerator and beverage centers. One zone, one set of POWER, WARMER and COLDER keys, and no defrost heater: the control simply keeps the compressor off until the coil has warmed above about 38°F.
- UC-24C and UC-24CI: the refrigerator and freezer combinations, with separate WARMER and COLDER keys for each zone. One sealed system with the coil on the freezer side, a heater defrost that adapts to use, and a motorized baffle that meters cold air to the refrigerator. The CI adds an ice maker.
- Two UC-24 eras: before serial 3603000 and after it. The later units have a smaller compressor and different sealed-system parts, but the code list is the same in both.
- UC-15I ice machines: the UC-15I, the outdoor UC-15IO and the drain pump versions UC-15IP and UC-15IPO. No numbered codes; see the ice machine section below.
- Other lines: Integrated ID drawers are on Integrated error codes, UW-24 wine units on wine storage error codes. The old 200 series runs on a thermostat with no codes, and newer Designer undercounter models use their own control, which we read on site.
What a UC-24 shows you without any service mode
A flashing SERVICE means a long compressor run and a steady one means stored codes; the service light page explains both across the series. The rest you can read on an undercounter:
- Display and light on, cabinet warm: possibly showroom mode, a setting that runs the lights and display with the compressor off. If the owner's guide check shows it is not, treat it as a fault and call.
- Everything dark: the unit may be switched off at POWER; otherwise check the breaker and, on bar and outdoor circuits, the GFCI.
- Compressor quiet for a while after a long run: on refrigerator and beverage models that is the off-cycle defrost waiting for the coil to warm, and it is normal.
How the codes are read
The numbered codes appear only in the UC-24 diagnostic mode, ahead of the actual temperature readings. They are cleared by hand after the repair, with a key combination that differs between the combination and single-zone models.
The control also keeps a temperature log with event markers, which separates an old event, such as a door that stood open during a party, from a fault still going on. A new UC-24 board does not know whether it sits in a beverage center or a combination until it is set to that model, which decides whether it runs one zone or two and which defrost it uses; we set it before we leave.
UC-24 code list
Both UC-24 eras use the same list. The numbers are the ones the later 600 and 700 controls use, so this section covers only what differs on an undercounter: which models can log each code and what you notice in the kitchen.
Sensors: 05 to 08
| Code | Which UC-24 logs it | What it points to, and what to do |
|---|---|---|
| 05 | All UC-24 | The refrigerator zone's air sensor, so that zone may drift warmer or colder than its setting. Check it with a thermometer and book a visit. |
| 06 | UC-24R, UC-24RO, UC-24B and UC-24BG only | The coil sensor that tells the off-cycle defrost when the coil has warmed up, so frost can build on the back wall. Book a visit. |
| 07 | UC-24C, UC-24CI | The freezer zone's air sensor. Watch the freezer temperature and call. |
| 08 | UC-24C, UC-24CI | The freezer coil sensor, which tells the heater defrost when to stop. Expect frost on the coil cover and call before it ices over. |
Defrost: 20 to 24, combinations only
| Code | What it means | What to do |
|---|---|---|
| 20 to 23 | The control could not confirm the freezer defrost heater circuit, or the defrost ran too hot | On a UC-24C or UC-24CI the refrigerator section usually warms first. Most often the heater, its safety thermostat or a connection. Call. |
| 24 | The defrost ran its full time and the coil stayed frosted | A weak heater, or ice packed on the coil after the door stood open. Check the seal, then call. |
The same numbers on a 600 or 700 are explained in more detail on 600 and 700 series diagnostics.
Compressor run, and the unused 30
| Code | What it means | What to do |
|---|---|---|
| 30 | Not used on the UC-24. The UC-24CI ice maker runs on its own thermostat and timer, so this code does not apply. | For ice problems, see Sub-Zero ice maker repair. |
| 40 | The freezer side kept the compressor running far longer than normal | Clean the grille with the breaker off, check the door closes fully, call if SERVICE keeps flashing. |
| 50 | The refrigerator side kept the compressor running far longer than normal | The same checks; on a beverage center, also look for a bottle holding the door open. |
What UC-24 codes usually turn out to be
A flashing SERVICE and 50 on a refrigerator or beverage center
What it usually is: the kickplate grille and condenser packed with lint, a door that drifts open under a heavy door shelf, a flattened gasket, or a cabinet restocked with a case of warm cans before a party. Bars, outdoor kitchens and homes with pets see it most. A leak is further down the list, but these small systems hold very little refrigerant, so even a slow leak soon shows up as long runs.
What you can check: with the breaker off, vacuum the grille face; then let the door go from halfway and see whether it closes. See the condenser cleaning guide and door not closing.
What we do: clean the condenser and fan, check the seal and closer, and measure the recovery before we clear the code.
A 40 or a defrost code on a UC-24C
What it usually is: a failed defrost heater or its safety thermostat, a freezer coil sensor, or a blocked drain. Because the refrigerator zone is cooled by air from the same coil, the first thing owners notice is often a warm refrigerator section while the freezer still feels cold. A baffle stuck shut or a stalled fan gives the same picture.
What you can check: frost on the freezer coil cover, water on the cabinet floor, and whether the door seals all the way round.
What we do: test the heater, terminator, sensor, baffle and fan, replace the part that failed, thaw the coil and watch the next defrost. More on Sub-Zero frost buildup.
A sensor code with normal cooling
What it usually is: a sensor that dropped out once, a loose connector, moisture in a connection on outdoor units, or a code left from an earlier repair.
What you can check: a thermometer in the cabinet for a day; if it agrees with the display and the setting, the visit can wait.
What we do: read the log to see when it happened, measure the sensor, and replace it or repair the connection. See outdoor kitchen refrigeration repair for units outside.
UC-15I ice machine: reading it without codes
The UC-15I service manual has no fault-code table. The machine has a user panel and a filter indicator, and a technician diagnoses it from how it behaves. It sprays water into the cube molds of a chilled evaporator for roughly 15 to 35 minutes depending on room and water temperature, then sends hot gas through the evaporator for a few minutes to release a batch of 16 cubes. A thermostat in the bin stops production when ice reaches it and restarts it when the level drops. In a 70°F room it makes about 50 pounds a day; at the grille of a hot outdoor kitchen, much less.
| What you see | What it usually points to | What you can do |
|---|---|---|
| Bin empty, but the machine hums | Water is not coming in, the water pump has stopped, a valve is stuck in the release cycle, or a refrigeration fault | Make sure the supply valve is open and the filter is not years old. Low water pressure also stops the fill, for example from a partly closed valve or a kinked supply line. |
| Less ice than it used to make | A dirty condenser, hot air at the grille, scale, or weak water flow | Clean the condenser behind the kickplate with power off. Expect less ice in summer heat. |
| Cloudy, hollow or undersized cubes | Not enough water reaching the molds, a clogged filter, or mineral scale | Replace the filter and book a descale. |
| Water on the floor or standing in the bin | A blocked gravity drain or, on the P models, a failed drain pump | Shut the water supply and call. See Sub-Zero leaking water. |
| Filter light on | The water filter is due, normally every six months | Replace the cartridge as the owner's guide describes. |
| Ice stays stuck in the molds | Scale in the cube molds or a harvest problem | Note when it was last cleaned and descaled. Do not pry at the ice. |
| Cubes fused into one slab | The freeze cycle runs too long and needs adjusting, or a sensor reads wrong | Book a visit; this is a technician adjustment. |
| Condensation on the door panel | A gasket or door that is not sealing, or a custom panel that does not fit well | Check that the door closes fully against its gasket. |
| Completely dead | Breaker, GFCI or the machine's switch; less often a fuse or board | Check the breaker and reset the GFCI once. If an outdoor unit keeps tripping it, have an electrician check the circuit before you reset it again. |
Cleaning and sanitizing the water system every six months prevents most of these, with a deeper yearly cleaning by a technician. Later UC-15I production uses R290 refrigerant, which is flammable, so the sealed system on those machines is strictly a technician's job. More on Sub-Zero ice maker repair and ice maker repair.
Stay safe. The UC-15I control board stays live with the machine's switch off, so turn the breaker off before you vacuum its condenser. The condenser fins behind a kickplate are sharp. Do not pull a UC-24 out past its anti-tip bracket; a full cabinet can tip forward.
What undercounter repairs cost
The service call is $79. It covers the visit and the diagnosis, including reading the stored codes and the temperature log, and it is applied to the repair once you approve the written price. Typical ranges for undercounter refrigeration and ice machines:
Wine storage and undercounter refrigeration repair
| Repair | Typical price, parts and labor |
|---|---|
| Fan motor | $300 to $550 |
| Temperature sensor | $250 to $450 |
| Door gasket | $300 to $550 |
| Control board or display | $550 to $1,100 |
| Drawer slide or door hinge | $300 to $600 |
| Sealed-system repair (leak, compressor) | $1,200 to $2,800 |
Built-in and undercounter ice maker repair
| Repair | Typical price, parts and labor |
|---|---|
| Descale and sanitize | $250 to $450 |
| Water valve | $350 to $600 |
| Water pump or drain pump | $400 to $700 |
| Bin thermostat or level sensor | $300 to $550 |
| Control board | $550 to $1,000 |
| Sealed-system repair | $1,200 to $2,500 |
Typical Orange County ranges for parts and labor. The $79 service call is applied to any of them. Parts that ship from the manufacturer and older or discontinued models can run higher. You get the exact written price after the diagnosis and before any work starts.
See also pricing, built-in refrigerator repair, undercounter repair and every line on Sub-Zero repair.
Talk to the technician first
Monday to Saturday, 8 AM to 7 PM. The $79 service call is applied to the repair.
Sub-Zero undercounter codes: questions
Which UC-24 models can show freezer or defrost codes?
Only the UC-24C and UC-24CI combinations. A UC-24R, UC-24RO, UC-24B or UC-24BG has no freezer and no defrost heater, so its codes come from the refrigerator sensors and long compressor runs.
What does code 50 mean on a Sub-Zero beverage center?
The refrigerator side ran its compressor far longer than normal. It is most often a clogged kickplate grille, a door that does not close or a heavy load of warm drinks, not a failed compressor.
Why does my UC-24C refrigerator get warm while the freezer stays cold?
Both zones are cooled by one coil on the freezer side. When that coil frosts over or the baffle and fan stop moving air, the refrigerator zone warms first. Defrost codes often come with it.
Is the code list different before and after serial 3603000?
No. Both UC-24 eras use the same numbers. The sealed-system parts and compressor changed, which matters when we order parts, not when we read codes.
Can a power outage set the SERVICE light on a UC-24?
It can. A long outage or a door left open warms the cabinet, and the compressor then runs long enough to log a run code. If temperatures recover and stay normal, it was a one-time event.
Does the Sub-Zero UC-15I have error codes?
Its service manual has no numbered code list. We diagnose it from what it does: whether it runs, fills, freezes, releases and drains, and what the cubes look like.
Why is my UC-15I running but the bin stays empty?
Most often water is not reaching it: a closed supply valve, a clogged filter or low pressure. If those are fine, the cause is usually the water pump, the harvest valve or scale in the cube molds.