The most common symptom of defrost problem in your refrigerator is a complete and uniformly frosted evaporator coil. Frost may also be seen on the panel covering the evaporator or cooling coil. During the refrigeration cycle of a refrigerator, moisture in the air freezes and sticks to the evaporator coils as frost The refrigerator has to go through a defrost cycle to melt this ice that continues to build up on the evaporator coils from the moisture in the air. If the refrigerator has a defrost problem the frost collected on the coils will not melt. Sometimes frost builds up to the point that it blocks airflow and the refrigerator stops cooling completely.

Refrigerator defrost problem is difficult to fix and most of the time require a refrigerator repair expert to identify the root of the problem.
Following are 3 reasons behind refrigerator defrost problem
1. Faulty defrost timer
In any frost free refrigerator there is a defrost system which controls the cooling and defrost cycle. The components of the defrost system are: a defrost timer and a defrost heater. A defrost timer switches the refrigerator between the cooling and defrost mode. If it goes bad and stops at cooling mode, it causes excessive frost to build up on the evaporator coils which reduces the air flow. Or when it stops at the defrost mode it melts all the frost and does not go back to the cooling cycle. A broken defrost times prevents the refrigerator from cooling efficiently.

Frigidaire 215846604 Defrost Timer
Refrigerator defrost timerThis is a genuine replacement part. The model number and name for the following item is: Frigidaire 215846604 Defrost Timer
Some more recommended defrost timers for refrigerators:
- Supco EDT11 Timer Defrost
- Ultra Durable W10822278 Refrigerator Defrost Timer by Blue Stars – Exact Fit for Whirlpool KitchenAid Kenmore Refrigerators/Freezers – Replaces PS11723171 945514 482493 R0950217 2188372
2. Defective defrost heater
A defrost heater melts the frost developed over the evaporator coil. But if it goes bad frost does not melt and excessive frost accumulates on coils reducing the cool air flow inside the refrigerator.
So when either of the 2 components i.e. defrost timer or defrost heater go faulty, the fridge does not understand when to cool and when to defrost.

FRIGIDAIRE 242044020 Defrost Heater Assembly
Refrigerator defrost heater assemblyThis is a genuine replacement part. The model number and name for the following item is: Frigidaire 242044020 Defrost Heater Assembly
Our other recommendations:
- WR51X10055 Refrigerator Defrost Heater Replacements WR55X10025 Refrigerator Temperature Sensor WR50X10068 Defrost Thermostat Compatible with general Electric Hotpoint Refrigerators Replaces WR51X10030
- [NEW UPGRADED] WR51X10055 Defrost Heater Enhanced Durability with METAL SHIELD Replacement Part by Blue Stars – Exact Fit For GE & Kenmore Refrigerators – Replaces AP3183311 914088 AH303781 EA303781
3. Defective thermostat
If the refrigerator does not defrost, the defrost thermostat might be defective. In a defrost system, the defrost heater turns on several times in a day to melt away the frost developed on the evaporator coil. This defrost heater is connected to a defrost thermostat. The defrost thermostat senses the temperature of cooling coils. When the cooling coils become cold enough, thermostat sends signal to defrost heater to turn on. If the thermostat is defective it may not be able to sense the temperature of coils and then won’t turn on the defrost heater. If the defrost heater doesn’t turn on, the refrigerator will never start the defrost cycle and will eventually stop cooling.

BluStars 2198202 Refrigerator Cold Control Thermostat
Refrigerator thermostatThe replacement part is made from durable high-quality material and well-tested by the manufacturer - Meets OEM standards - Ensure long-lasting and effective performance. This part fixes the following symptoms: Will not start | Fridge too warm | Freezer section too warm | Fridge too cold
Our other recommendations:
- AquaMonica Universal fridge freezer Refrigerator Thermostat WPF-22 Temperature Control 220-250V/5(4) A 1PCS
- 2198202 Refrigerator Cold Control Thermostat – Exact Fit for Whirlpool,Kenmore,Sears. Replaces Part Numbers 2161284,2198201,AP3037004,WP2198202,AP6006166,PS11739232
The above are some common reasons behind refrigerator not defrosting , problem please leave your comment below if you have come across some other reasons for not defrosting, so we can update this list!
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I appreciate your clear and concise breakdown of the symptoms associated with a malfunctioning defrost timer. Your blog has empowered me to identify and address this problem in my refrigerator
We really appreciate your assistance in getting our refrigerator working again. I’ve been trying to use a thermos, but I have no idea what I’m doing. As a result of my inquiry, I landed on your page.
I think the main reason is the defrost thermostat might be defective.
we’ve changed the thermostat numerous times without success. Additionally, gas work was completed, but the ice problem persisted.
The image in this article depicting a defrost issue is not a defrost issue. Their image depicts low pressure inside the refrigerant system that is either caused by the fan not working or a “system issue”. A “system issue” is not a DIY repair. If you have that problem with no manufacturer warranty and you are sure the fan is working, I’d suggest buying a new fridge. An issue with your defrost system will have frost built up either on the bottom of the evaporator near the heating element or frost will be built up evenly from bottom to top. A simple way to remember this is there will be no frost near the element if the element is working. Good luck on your repairs!
Does continuity test ensures functioning of defrost heating element (tube) ?
Thanks for your information. My Samsung (RH25H5611SR) periodically ( every2-3weeks) shows error in temperature and fridge real temperature is 58F ( Freezer side normal). After plug off unit one day, it turns work well. Could you please give any advice.
I have been having issues with my freezer frosting over the coils, but the fridge not cooling enough. I unplugged the unit and allowed the everything to defrost for 24 hours. After cleaning it and another 24 hours had passed, its doing the same thing.
It sounds like it could be any of these issues but am unsure what to do or if I need to buy a new unit.
Thanks,
Isaiah
Thank you so much for solving a refrigerator problem for us. I try to use a thermos but; I don’t have any idea about it. So then I search and reach here on your site. Your blog helps me to find a good way. I’m happy to read it. I hope you will provide soon more information about it.
Thanks for these imformations , I think you cover almost the reasons that leads to defrost problems.
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Thanks, so many times we changed the thermostat but no result getting. Also done gas work but still problem of iced all through.