The situation when in the upper part of the refrigerator compartment the products are cooled normally, but the lower chamber (freezer) stops freezing, is a classic sign of a refrigerant circulation problem or a failure in the control system. Often, equipment owners notice that the ice in the freezer is melting, but in the refrigerator, on the contrary, it may be too cold or, conversely, warm. This indicates that cooling cycle is broken and the refrigerant does not reach the evaporator in the required volume or is not removed from it.
The first thing that needs to be done when a problem is detected is to carry out an initial visual diagnosis. Check to see if the light is on, if the door closes tightly and if there is any frost in one of the compartments. Modern models with the No Frost system they can hide ice inside the case, so external cleanliness does not mean serviceability. If you hear that the compressor works without interruption or, on the contrary, turns on extremely rarely, these are important diagnostic symptoms.
In most cases, the reason lies in one of five main malfunctions: freon leak, capillary tube clogged, sensor failure, defrost heating element failure or compressor malfunction. It is difficult to independently determine the exact cause without a pressure gauge manifold, but by indirect signs you can narrow the search. If the lower chamber has completely defrosted in a few hours, and the compressor is silent, the problem is most likely electrical (sensor or module); if it works constantly, it is mechanical (leakage or blockage).
⚠️ Attention: If When attempting to defrost yourself, never use sharp objects to chip ice. A breakdown of the evaporator will lead to an instant release of freon and will require expensive soldering and refilling.
Tightness failure and refrigerant leak
The most common reason why the lower chamber stops freezing is a banal leak refrigerant. Freon circulates in a closed loop, and if a microcrack appears in the system, the pressure drops and the gas stops reaching remote areas of the evaporator. In two-chamber refrigerators, the evaporator is often located in the freezer compartment or in the partition between the chambers. When there is a leak, the compressor tries to compensate for the lack of pressure, working for wear, but no cold is produced.
Leaks often occur in places where pipes are soldered, in the foamed part of the body (due to corrosion) or in the heating circuit of the door perimeter. If your refrigerator has a weeping evaporator, you may notice a bulge in the back wall inside the chamber. In models with No Frost leakage is more difficult to notice, since the evaporator is hidden behind a plastic panel. An indirect sign is that the capacitor (grid at the back) is only a third or half hot, whereas normally it should be warm along its entire length.
Diagnostics of a leak requires the use of a leak detector or a soap solution, which is used to treat all visible connections. However, if the tube bursts inside the housing, repairs become difficult: it is necessary to open the thermal insulation, install a new evaporator, or reposition the circuit. This is a labor-intensive process that requires evacuation of the system and precise filling with gas.
Clogged capillary tube and problems with the filter
The second most common reason for stopping the cooling of the lower chamber is clogged capillary tube. This part is a thin copper pipe that regulates the pressure of freon before it enters the evaporator. Over time, oil oxidation products, moisture, or solder microparticles may accumulate in the system, which clog the narrow section of the tube. As a result, freon cannot circulate in the required volume.
Symptoms of a blockage are often confused with a leak, but there is a key difference. If clogged, the compressor can also run for a long time, but the condenser (rear grill) will only be warm at the beginning, and then cold. In addition, when the unit is operating, a characteristic gurgling or gurgling sound may be produced that was not there before. This indicates that the gas is trying to overcome the obstacle.
To eliminate this malfunction, the technician needs to:
- 🔧 Pump out all the freon from the system and carry out high-pressure nitrogen purge of the circuit.
- 🔧 Replace the filter drier, since the old one will no longer be able to effectively remove moisture.
- 🔧 Vacuum the system for 30-40 minutes to remove residual moisture and air.
- 🔧 Fill the refrigerator with new freon strictly according to the weight indicated on the nameplate.
⚠️ Attention: Purging the system with nitrogen should only be carried out by a professional equipment. The use of homemade compressors can drive moisture deeper into the system, which will lead to the formation of an ice plug and repeated repairs in a month.
Malfunction of the defrost system (for No Frost refrigerators)
If you have a refrigerator with the system No Frostand it stops freezing, in 80% of cases the fault of the system is to blame defrost. The operating principle of such units is that frost growing on a hidden evaporator is periodically melted by heating elements. If this process is disrupted, the evaporator becomes covered with ice, which blocks air circulation. As a result, the cold simply does not enter the chamber, although the compressor can work properly.
The defrost system includes three main elements: the evaporator heating element, the drip heating element (groove) and the defrost sensor (thermostat). If the heating element burns out, the ice does not melt. If the defrost sensor “sticks” or fails, it does not give a command to turn on the heating or, conversely, does not turn it off. Also, the fuse that is in the circuit to protect against overheating often breaks.
To check this version, you need to remove the back panel in the freezer. If you see a thick layer of ice hiding the radiator fins, then air is not passing through. In this case, you need to test all elements of the defrost circuit with a multimeter. The normal resistance of the heating element is usually from 200 to 400 Ohms, depending on the power.
☑️ Diagnostics of the No Frost system
Failure of the sensors and thermostat
The electronics of modern refrigerators completely control the cooling process, relying on sensor readings. If temperature sensor the lower chamber transmits incorrect data (for example, it shows that it is -20°C, although in fact it is 0°C), the control module simply will not turn on the compressor. A mechanical thermostat behaves similarly in older models: if its sensitive element has lost its properties, the circuit does not close.
Often the problem lies not in the sensor itself, but in broken wiring or oxidation of contacts. Vibration during compressor operation gradually loosens the connections. In electronically controlled refrigerators (where the temperature is set using buttons on the display), the refrigerator itself may fail. In this case, the refrigerator may “freeze” in standby or defrost mode. control module. In this case, the refrigerator may become stuck in standby or defrost mode.
Sensors are diagnosed by measuring their resistance at different temperatures. Resistance tables (RTD) vary from manufacturer to manufacturer (Indesit, Samsung, LG, Bosch). If the sensor resistance is infinite or zero, it requires replacement. It is important to use original spare parts or high-quality analogues, since cheap sensors have a large error.
Problems with the compressor and start relay
The compressor is the “heart” of the refrigerator, creating pressure in the system. If it does not start, hums but does not turn on, or runs with strong vibration and knocking, the lower chamber will not freeze. Often the culprit is not the device itself, but start relay a small block on the motor body that gives the starting impulse. If the relay is burned out, the compressor hums for a few seconds and clicks, trying to start, but without success.
A more serious problem is an interturn short circuit of the compressor windings or jamming of the piston group. In this case, the motor may hum, be hot, but not develop the required pressure. You can test the compressor by disconnecting it from the system and connecting it directly to the network via a test cord with a capacitor. If it runs smoothly when free running, and the pressure at the outlet of the discharge tube is strong, then the problem is inside the refrigeration circuit.
Replacing a compressor is a complex process that requires:
- ⚙️ Draining the old oil and freon.
- ⚙️ Dismantling old motor and installation of a new one (often requires alteration of pipelines).
- ⚙️ Soldering connections in a nitrogen environment (to prevent tubes from oxidizing).
- ⚙️ Long-term vacuuming (at least 40 minutes) to remove moisture.
⚠️ Attention: If the compressor is replaced without using nitrogen during soldering, oxides are formed inside the system, which will quickly lead to clogging of the capillary tube and repeated failure of the expensive unit.
Is it possible to replace the compressor yourself?
Theoretically, yes, if you have the skills to solder copper pipes and equipment. However, without a vacuum pump and a pressure gauge station, high-quality refueling is impossible. Residual moisture in the system will kill a new compressor within 2-3 months of operation.
Diagnostic table of faults
For convenience, we systematize the main symptoms and probable causes in a table. This will help you quickly find your bearings before calling a technician.
| Symptom | Probable cause | Difficulty of repair | Necessary equipment |
|---|---|---|---|
| The compressor is humming, but does not start | The starting relay or compressor wedge is faulty | Medium | Multimeter, test cord |
| The compressor runs constantly, there is no cold | Leakage freon or clogged capillary tube | High | Leak detector, nitrogen, vacuum sealer |
| There is a coat of ice in the freezer, no cold | Malfunction of the defrost system (No Frost) | Low | Multimeter, screwdrivers |
| The refrigerator rarely turns on, it’s warm inside | The thermostat or sensor is faulty | Low | Multimeter, hair dryer (for checking) |
| A gurgling sound is heard, the cold is weak | Partial blockage or lack of freon | High | Pressure gauges, scales |
Frequently asked questions and answers (FAQ)
Why does the lower chamber not freeze after defrosting?
If after complete defrosting (more than 24 hours) the refrigerator does not start to freeze, there may be ice left in the system that has not had time to melt (the condensate drain channel is clogged), or there is a power surge that damages the control module. Also, during defrosting, the temperature sensor could be damaged.
Is it possible to operate the refrigerator if the freezer does not freeze?
For a short time - yes, the food in the refrigerator compartment may not spoil. However, prolonged operation in this mode is dangerous for the compressor, which may overheat while trying to gain temperature. In addition, bacteria can multiply in the freezer and an unpleasant odor may appear.
How long do you need to wait for the cold after turning it on?
The time for first entering the mode depends on the model and the room temperature. This usually takes from 2 to 12 hours. If after a day the bottom chamber remains warm, and the food is defrosted, there is a malfunction.
Why does the bottom not freeze in a refrigerator with one compressor?
In single-circuit systems, cold from the freezer enters the refrigeration compartment. If it is warm below, it means that the air circulation is disrupted (the channels are clogged with ice) or the damper-regulator that blocks the flow of cold air is faulty.