The situation when the upper part of the refrigerator is working properly, but in the lower chamber the food begins to deteriorate or melt, often causes panic among equipment owners No Frost. This is a classic symptom indicating a problem in the circulation of cold air between the evaporator and the freezer compartment. Unlike drip systems, here the cold is forced in, and any failure in this chain immediately affects the temperature below.
Before calling a technician, it is necessary to carry out an initial diagnosis, since the cause may lie in either a simple drainage blockage or a failure of the electronic control module. Air circulation is the heart of the system No Frost, and if it is broken, the compressor can work non-stop, trying to compensate for the lack of cold, but this will not give any result. Understanding the operating principle will help you save time and money on diagnostics.
In this article we will analyze in detail the mechanical and electrical causes of the malfunction, methods for identifying them and ways to eliminate them. You will learn how to check Defrost heating elementwhy the fan may stop and what to do if the timer decides to “rest”. We will also discuss cases when the problem lies in a refrigerant leak, which requires professional intervention.
The principle of operation of the No Frost system and the path of cold
To understand why the bottom stopped freezing, you need to imagine how the air moves inside the chamber. In refrigerators with a No Frost system (which translates as “no frost”), the main heat exchanger, or evaporator, is hidden behind a plastic panel at the top of the freezer compartment or behind the back wall. The fan forces air through this ice radiator, cools it and directs it down into the freezer compartment, and from there into the refrigerator compartment.
If the refrigerator has stopped freezing in the lower part, this almost always means that the cold flow does not physically reach there. Temperature control damper or the air supply channels may be blocked by ice. In normal operation, the ice that accumulates on the evaporator is periodically melted by the heating element, and the water goes into the drain. If this cycle is disrupted, the channels become overgrown with a “fur coat”, and the air stops circulating.
⚠️ Attention: If you hear that the fan is humming or crackling, but the cold is not coming out, perhaps its blades are touching frozen ice. In this case, the operation of the equipment may lead to the combustion of the fan motor.
It is important to note that in two-compressor models the situation may be different: there a separate circuit is responsible for the bottom, and the problem may be associated with it. However, in most modern single-compressor models Indesit, LG or Samsung one cooling system is used for the entire volume, and a violation of the flow distribution is the most common cause of a warm bottom.
Mechanical blockages: ice in the channels and drainage
The most common reason why a refrigerator No Frost does not freeze well at the bottom is the formation of an ice plug in the air ducts. This happens when the defrost system does not work correctly: water from melting ice does not have time to drain and freezes in the air supply channels. Over time, the gap narrows completely, and cold air remains in the upper part, without reaching the lower shelves.
Often the culprit becomes drain hole. If it's clogged with crumbs, mold or ice, the water has nowhere to go and freezes right under the evaporator, cutting off air flow. Visually this may not be noticeable, since the evaporator is covered with a plastic cover. You will need to remove the back panel in the freezer to assess the extent of the icing.
- ❄️ The ice on the evaporator is uneven, with a thicker layer on one side.
- 💧 Water under the drawers or at the bottom of the freezer, which turns into lump.
- 🌬️ Weak air pressure from the supply holes even with the fan running.
To eliminate this problem, it is often enough to completely defrost the refrigerator. It is necessary to turn off the device from the network, open the doors and leave it for at least 24 hours (preferably two days). Only long-term defrosting will allow the ice to melt in hard-to-reach channels where heat from the room does not penetrate.
Why can’t you defrost with a hairdryer or boiling water?
Using a hairdryer or hot water to speed up defrosting can lead to deformation of the plastic parts of the housing and damage to the evaporator tubes. A sharp temperature change is dangerous for the refrigerant and plastic.
Malfunctions of the defrost system: heating element, timer and sensors
If after a 24-hour defrost the refrigerator began to work normally, but after 1-2 weeks the problem with the lack of cold below returned, it means that the automatic defrosting system is faulty. It consists of several key elements: a heater (heating element), a defrost sensor (thermostat) and a control element (timer or electronic module).
Defrosting heating element is a tubular heater located under the evaporator. If it burns out, the ice on the evaporator does not melt during the defrost cycle, but only builds up. You can check it with a multimeter for an open circuit. The resistance of a working heating element is usually from 200 to 500 Ohms, depending on the power and model of the refrigerator.
The second important element is defrost sensor (thermostat). It controls the temperature of the evaporator and gives a command to turn the heating element on or off. If the sensor is stuck in the "on" position, the heater will heat constantly (which is rare, but possible), or, more often, it will not allow heating to start when needed. As a result, the evaporator becomes overgrown with ice and stops passing air.
☑️ Diagnostics of the defrost system
The third component is a timer or electronic module management. Older models have a mechanical timer that switches between “cooling” and “defrosting” modes. If it gets stuck in cooling mode, defrosting will never start. In modern models (Bosch, Electrolux), this is done by electronics, and a failure in its operation can lead to similar consequences.
Problems with the fan and air supply damper
The driving force in the system No Frost is the fan. It is this that creates the pressure necessary to pump cold air through the entire chamber. If the fan does not work, cold air remains at the evaporator (at the top), and warm air remains at the bottom. In this case, the compressor may hum without interruption, trying to cool the sensors that do not feel cold due to lack of circulation.
The reasons for stopping the fan can be different:
- 🔌 Broken wiring or oxidation of connector contacts.
- 🧊 Freezing of the blades to the body or frozen ice.
- 🔥 Failure of the motor windings (combustion).
Another element that affects the distribution of cold is air supply damper (damper). It is located on the border between the freezer and refrigerator compartments. The damper opens and closes at the command of the thermostat, regulating the amount of cold air. If the damper mechanism is stuck in the closed position, cold simply does not flow into the refrigerator compartment (or to the bottom of the freezer, depending on the design).
⚠️ Attention: When diagnosing the fan, do not try to turn its blades with your fingers while the refrigerator is plugged in. This may cause injury or short circuit. Always turn off the power to the appliance before removing the panels.
Checking the fan is simple: when the freezer door is open (and the door sensor is pressed, if there is one), you should hear the characteristic noise of the motor operating. If there is silence, you need to check the presence of voltage at the terminals. If there is voltage but no rotation, the fan needs to be replaced.
Freon leak and problems with the compressor
The most unpleasant scenario is when the refrigerator No Frost stops freezing below - this is a refrigerant (freon) leak. In such systems, the evaporator is often made in the form of a loop foamed into the wall or a hidden coil. When there is a leak, the pressure in the system drops, and the freon simply does not reach the end of the circuit, evaporating in its first part. As a result, the upper part (where the entrance to the evaporator) may be cold, and the lower part - warm.
It is difficult to diagnose a leak on your own, but there are indirect signs:
- 🌡️ The condenser (grid at the back) is only partially warm or cold.
- 🔊 The compressor works constantly without turning off.
- 🧊 The evaporator in the freezer is unevenly covered with frost (only at the entrance of the tubes).
If the problem is in the compressor (for example, loss of compression or interturn short circuit), the symptoms will be similar. However, compressors break less often than leaks occur through microcracks in the foamed part or in solder areas. Repair in the event of a leak requires calling a technician, evacuation of the system and refilling with freon.
Diagnostic table: symptoms and probable causes
For ease of troubleshooting, the main symptoms are summarized in a table. This will help narrow down your search before calling a specialist or purchasing spare parts.
| Symptom | Probable cause | Difficulty of repair | Necessary actions |
|---|---|---|---|
| The fan does not noisy, there is no cold anywhere | The fan is faulty or there is no power supply | Low | Replacing the fan, checking the circuit |
| There is cold only at the top, the bottom is warm | Clogged channels ice, faulty damper | Medium | Defrost 24 hours, check the damper |
| The compressor hums non-stop, there is little cold | Freon leak, broken heating element defrost | High | Call a technician, search for leaks |
| Periodically appears and disappears | Failure of timer, sensor or module | Medium | Diagnostics of electronics with a multimeter |
It is important to understand that some faults, such as freon leakage or compressor failure, require special equipment for repair. Attempts to fix them yourself without skills and tools can lead to the final failure of the equipment.
When you need to call a technician: critical breakdowns
Despite the possibility of self-diagnosis, there are situations when professional intervention is indispensable. If after completely defrosting (more than 24 hours) and checking the fan the problem does not go away, it is most likely due to a hidden leak or complex electronics. The technician will be able to test the tightness of the system and pinpoint the location of the leak.
A specialist’s help is also needed if the compressor needs to be replaced or the system needs to be refilled with refrigerant. These operations require a vacuum pump, a pressure gauge station and a license to work with freons. In addition, in modern models with inverter compressors, diagnostics are carried out through special service codes read from the control board.
⚠️ Attention: Modern refrigerators use new types of refrigerants (R600a), which are explosive when concentrated. Self-refueling without following the technology can be dangerous to health and life.
Do not ignore the first signs of a malfunction. If the refrigerator starts working longer than usual or there is a strange noise, this may be a harbinger of a serious breakdown. Timely repairs are cheaper than replacing a burnt-out compressor or buying a new unit.
Frequently asked questions (FAQ)
Why, after defrosting, did the refrigerator stop freezing again after a week?
This is a sure sign of a malfunction of the defrosting system. Most likely, the heating element of the heater has burned out, the defrost sensor has failed, or the timer does not switch modes. Ice again accumulates on the evaporator and blocks the air supply channels.
Is it possible to operate a refrigerator if it does not freeze at the bottom, but the top part works?
For a short time - yes, but not for long. The compressor will work non-stop, trying to gain temperature, which will lead to overheating and possible combustion. In addition, the food in the lower chamber will spoil.
How can you tell if the No Frost fan has burned out?
When the freezer door is open (and the light switch/door sensor is pressed), you should hear the hum of the running fan. If there is silence and there is frost on the evaporator, the fan does not work. It can also crack if frozen.
How long does it take to defrost a No Frost refrigerator?
Minimum 24 hours, preferably 48 hours. The ice in the channels and behind the panels is melting slowly. If you hurry and turn on the device earlier, the water in the narrow channels will freeze again, and the problem will not be solved.
Why is there ice in the freezer, but warm in the refrigerator?
In the No Frost system, this means that cold air does not circulate. Ice in the freezer is a working evaporator, but the fan does not move the air further, either the damper is closed, or the channels are clogged with ice.