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The back wall of an upright freezer with its cover off, the coil behind it buried in a thick white block of frost and a defrost heater visible along the bottom edge.

Sub-Zero code 24: the defrost did not warm the coil enough

Code 24 is Sub-Zero’s defrost underheat code on IC-27 columns and 700 Series models.

(844) 456-4651

Mon–Sat, 8am–8pm

  • Defrost system
  • Freezer defrost system repair
  • Source: Sub-Zero

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Three short steps, about a minute.

or call (844) 456-4651

What 24
actually means.

Code 24 is Sub-Zero’s defrost underheat code on IC-27 columns and 700 Series models. The heater ran but the coil did not warm as it should, which can leave ice on the evaporator and slowly cut airflow.

Sub-Zero freezer display

What to do when 24 shows on the freezer

Kind of codeDefrost system

A frost-free freezer warms its coil for a few minutes several times a day to melt the frost, and the control noticed that this did not happen or took too long. A heater that burned open, a defrost thermostat or a timer that stuck, or a drain frozen shut lets frost wrap the coil until air cannot pass. Chest freezers without automatic defrost do not show these codes; their frost comes off by hand.

Usually leads toFreezer defrost system repair

Repairing the heater, the defrost thermostat or sensor and the timer or board that keep ice off the hidden coil in a frost-free upright, column or undercounter freezer.

Shows up asFreezer Error Code

A freezer error code appears on the display: letters and digits, a flashing temperature, or a warning symbol, sometimes with an alarm and sometimes with the freezer still running.

MakeSub-Zero

Sub-Zero freezers repaired in the home, with the food kept shut in while the cause is found.

SourceSub-Zero answer: 700 Series error code 24

700 Series and IC-27 integrated columns (shown as 24).

Before you book,
in this order.

Each step comes from Sub-Zero's own guidance for 24 on its freezers. Follow it to the end: the last card says whether this is a visit.

01

Check the freezer temperature; if it is high, keep the door closed and book a visit.

02

If temperatures are close to normal, clean the condenser, then hold the door ajar alarm key for 15 seconds to clear 24 on a 700 Series.

03

Book a visit if 24, the Service light or rising temperatures come back.

Still there?

It usually turns into freezer defrost system repair. Book with the code and the model number.

What not to do

Code 24 is not the overheat code; that one is 21. It also does not mean the compressor has failed, although a frosted coil can make the freezer run longer.

What you may
notice with it.

The freezer problems 24 tends to arrive with. Answer these at the freezer before anyone is booked.

All problems

Before you call

Freezer Error Code

All 7 causes, cheapest first

It also comes with

The glowing control panel on the front of a stainless undercounter freezer drawer in a home bar, a blurred, unreadable code beside a flashing warning light, an owner's manual lying open with out-of-focus pages on the counter above. Problem

Freezer Error Code

7 causes, cheapest first

Where 24 usually leads

Freezer defrost system repair.

Defrost heater, defrost thermostat or timer · low to moderate.
Book a visit What the job involves

Sub-Zero
freezers.

Sub-Zero freezers repaired in the home, with the food kept shut in while the cause is found.

Sub-Zero freezer repair

More Sub-Zero codes

EC07EC08EC40212220 4 5095 1 0035 C 0090 5 80

Defrost system on other makes

Fisher & Paykel F2Marvel EdPerlick TEL
All 6 codes of this kind
A tall stainless steel built-in freezer column stands flush in white kitchen cabinetry in a US home, its door open on lit glass shelves and pull-out bins of frozen food. Sub-Zero builds this

Freezer column

A built-in, full-height freezer that stands alone in the cabinetry, often beside a matching fresh-food column, with a stainless or panel-ready door and an electronic control.

 Two stainless undercounter freezer drawers built into a US home bar island, the top drawer pulled out to show frost-free bins of ice cream pints and frozen fruit bags. Sub-Zero builds this

Undercounter freezer

A 15- to 24-inch freezer or a pair of freezer drawers built in under a counter, in a kitchen island, a home bar, a basement or a pool house, venting from the front.

In Sub-Zero's own words

Defrost underheat
Sub-Zero answer: 700 Series error code 24 Sub-Zero answer: 700 Series error code 24 Sub-Zero answer: IC-27 integrated columns error code 24

Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. 700 Series and IC-27 integrated columns (shown as 24).

Sub-Zero 24 freezer repair,
where we come out.

The same visit in every metro below: the code, the model number, and a diagnosis before any part is ordered.

All service areas

Tampa BayFL · 31 areas

OrlandoFL · 30 areas

Miami / South FloridaFL · 47 areas

New York MetroNY · 75 areas

HoustonTX · 36 areas

ChicagoIL · 50 areas

Los AngelesCA · 95 areas

San DiegoCA · 31 areas

San Francisco Bay AreaCA · 74 areas

A parent and a child packing summer berries into bags beside an open upright freezer in a tidy garage
For the heart of your home.

Questions
about 24.

Can I clear 24 myself?
Check the freezer temperature; if it is high, keep the door closed and book a visit. If it comes back, it needs a visit.
What does defrost underheat mean on a Sub-Zero freezer?
The defrost heater was switched on, but the coil stayed colder than the control expected by the end of the cycle. A weak heater, a limit that opens early or ice packed around the coil can all cause it.
Why does Sub-Zero ask me to clean the condenser for code 24?
Its steps for the 700 Series start with the condenser when temperatures are near normal, since a clean condenser takes load off the system. If the code comes back after that, the defrost parts need testing.
Could code 24 explain frost on the back wall of my Sub-Zero?
Yes. When each defrost falls short, frost can build on the coil and spread to the panel in front of it. A technician can confirm by checking the heater and the coil.

Back to your everyday

Still showing 24?

Book with the code or the alarm pattern written exactly as the freezer shows it, the full model number, and whether the food is still frozen hard — when there is a code, that is where the diagnosis starts.

Schedule a repair Call (844) 456-4651
(844) 456-4651 Schedule a repair