--- title: "Sub-Zero 20 4 50 on a Designer column: defrost timed out four times in a row" description: "What 20 4 50 means on Sub-Zero 20 4 50 on a Designer column: defrost timed out four times in a rows, what to check before booking, and when it is not a failure…" url: "https://freezerrepair.center/error-codes/sub-zero-20-4-50/" --- # Sub-Zero 20 4 50 on a Designer column: defrost timed out four times in a row Sub-Zero lists 20 4 50 for Designer DET and DEC models and older IT and IC units. ## What 20 4 50 actually means. Sub-Zero lists 20 4 50 for Designer DET and DEC models and older IT and IC units. It is logged when the cooling logic leaves defrost four times running because time ran out and the bimetal never tripped while the heater was on, which usually points to a heater that is not heating. Sub-Zero freezer display What to do when 20 4 50 shows on the freezer ### Kind of code Defrost 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 to Freezer 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 as Freezer 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. ### Make Sub-Zero Sub-Zero freezers repaired in the home, with the food kept shut in while the cause is found. ### Source Sub-Zero answer: Designer Series error 20 4 50 Designer DET and DEC models (including DEC column freezers) and Legacy Designer IT and IC models. Older 600, 700 and IC-27 units use two-digit defrost codes instead. ## Before you book, in this order. Each step comes from Sub-Zero's own guidance for 20 4 50 on its freezers. Follow it to the end: the last card says whether this is a visit. 01 Turn the breaker off for 30 seconds and back on, then keep watch on the display over the next day. 02 Look for frost behind the vents or a freezer that is getting slowly warmer, and move food to a cooler if it softens. 03 Book a visit if 20 4 50 returns, and note which door or drawer the display points to. ### Still there? It usually turns into [freezer defrost system repair](https://freezerrepair.center/services/defrost-system-repair/). Book with the code and the model number. ### What not to do This is not the door code or a sensor code; those start with 95 and 10 on Designer models. It also does not say the compressor is failing, only that defrost is not finishing normally. ## What you may notice with it. The freezer problems 20 4 50 tends to arrive with. Answer these at the freezer before anyone is booked. [All problems](https://freezerrepair.center/problems/) Before you call ### [Freezer Error Code](https://freezerrepair.center/problems/freezer-error-code/) [All 7 causes, cheapest first](https://freezerrepair.center/problems/freezer-error-code/) It also comes with - [**Heavy Frost Buildup in the Freezer**](https://freezerrepair.center/problems/freezer-frost-buildup/) - [**Standalone Freezer Not Freezing**](https://freezerrepair.center/problems/freezer-not-freezing/) Problem ### Freezer Error Code 7 causes, cheapest first Where 20 4 50 usually leads ## Freezer defrost system repair. **Defrost heater, defrost thermostat or timer · low to moderate.** Book a visit [What the job involves](https://freezerrepair.center/services/defrost-system-repair/) ## 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](https://freezerrepair.center/brands/sub-zero/) More Sub-Zero codes [EC07](https://freezerrepair.center/error-codes/sub-zero-ec07/) [EC08](https://freezerrepair.center/error-codes/sub-zero-ec08/) [EC40](https://freezerrepair.center/error-codes/sub-zero-ec40/) [21](https://freezerrepair.center/error-codes/sub-zero-21/) [22](https://freezerrepair.center/error-codes/sub-zero-22/) [24](https://freezerrepair.center/error-codes/sub-zero-24/) [95 1 00](https://freezerrepair.center/error-codes/sub-zero-95-1-00/) [35 C 00](https://freezerrepair.center/error-codes/sub-zero-35-c-00/) [90 5 80](https://freezerrepair.center/error-codes/sub-zero-90-5-80/) Defrost system on other makes [Fisher & Paykel F2](https://freezerrepair.center/error-codes/fisher-and-paykel-f2/) [Marvel Ed](https://freezerrepair.center/error-codes/marvel-ed/) [Perlick TEL](https://freezerrepair.center/error-codes/perlick-tel/) [All 6 codes of this kind](https://freezerrepair.center/error-codes/#family-defrost) 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. 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 > Zone cooling algorithm exits the Defrost state four consecutive times due to the timeout being reached [Sub-Zero answer: Designer Series error 20 4 50](https://www.subzero-wolf.com/assistance/answers/sub-zero/designer/designer-formerly-integrated-series-error-code-20-4-50) [Sub-Zero answer: Designer Series error 20 4 50](https://www.subzero-wolf.com/assistance/answers/sub-zero/designer/designer-formerly-integrated-series-error-code-20-4-50) Every code on this site is taken from the manufacturer's documentation, never from a forum or a parts listing. Designer DET and DEC models (including DEC column freezers) and Legacy Designer IT and IC models. Older 600, 700 and IC-27 units use two-digit defrost codes instead. ## Sub-Zero 20 4 50 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. 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Turn the breaker off for 30 seconds and back on, then keep watch on the display over the next day. If it comes back, it needs a visit. ### What does the bimetal have to do with Sub-Zero 20 4 50? The bimetal is a heat switch that trips when the coil has warmed enough during defrost. If it never trips across four cycles, the control concludes the heater is not doing its job. ### Does 20 4 50 apply to my DEC1850F column freezer? Sub-Zero names DEC models in its answer for this code, and the DEC column freezers belong to that family. The same code on an older IC column also carries the same meaning. ### Is it safe to reset Sub-Zero 20 4 50 and wait? A reset is Sub-Zero’s own first step. If the code comes back, waiting only lets more frost collect, so plan a visit before the freezer starts to warm. --- **[Read on the site: Sub-Zero 20 4 50 on a Designer column: defrost timed out four times in a row](https://freezerrepair.center/error-codes/sub-zero-20-4-50/)** **[Book a visit with FreezerRepair.center](https://freezerrepair.center/schedule/)**