The situation when you defrost the refrigerator, return the food, and it refuses to cool, causes panic. The indicators on the panel may be on, the light inside illuminates the shelves, but there is no characteristic hum of the compressor. This is a classic symptom indicating that the electrical circuit to the control unit is intact, but startup of the compressor is blocked or impossible. Most often, the problem lies in residual moisture or an electronics failure that occurred when the power was turned on. Moisture could get on the contacts of the sensors, and a voltage surge when connecting the plug to the socket could “knock down” the settings of the control module. It is important not to panic, but to consistently check the condition of the equipment. compressor blocked or impossible.
Most often, the problem lies in residual moisture or an electronic failure that occurred when the power was turned on. Moisture could get on the contacts of the sensors, and a voltage surge when connecting the plug to the socket could “knock down” the settings of the control module. It is important not to panic, but to consistently check the condition of the equipment.
In this article we will analyze in detail the mechanical and electrical causes of failure. You will learn how to independently diagnose a malfunction Evaporator heating element, check the thermostat and understand when expensive components need to be replaced. Remember that correct diagnostics will save you money on calling a technician.
Hidden moisture and short circuit of contacts
The most common, but common reason is that the unit is not completely dry. Even if you waited the required 24 hours, condensation moisture could remain in hard-to-reach places, especially around thermostat and the start relay. Water is a conductor and can create stray currents that block the engine from starting or trigger the protection.
Moisture often flows inside the thermostat housing if you used too much water during washing or directed the stream directly at the temperature controller. In this case, the contacts inside the device oxidize or close. The electronics sees incorrect temperature data and does not give a command to start the compressor, believing that there is already cold inside.
⚠️ Attention: If you suspect water getting inside the electrical components, do not under any circumstances try to force the switch on. Let the refrigerator sit in a warm, dry place for another 12 to 24 hours with the doors open. Using a hair dryer to dry internal components may melt the plastic elements.
To eliminate the problem, ensure maximum ventilation. Remove the back panel in the freezer (if accessible) and check that the sensors are dry. Sometimes it is enough to simply wipe the visible contacts with a dry cloth and leave the device unplugged for a day.
Failure of the electronic control module
Modern models Indesit, Bosch or Samsung equipped with sophisticated electronics. When defrosting, a banal power cut often occurs, and when turned back on, a power surge occurs. The brain of the refrigerator, or control modulecould perceive this as an emergency situation and go into protection mode.
In this mode, the system blocks the start of the compressor to prevent its breakdown. The light in the chamber is on because voltage is supplied to the lamp directly, bypassing the logical motor control chain. You can often reset the error programmatically, without disassembling the unit.
Try a full system reboot. To do this:
- 🔌 Unplug the refrigerator completely from the socket.
- ⏱️ Wait at least 15-20 minutes (this time is needed to discharge the capacitors).
- 🔌 Plug the device back into the network.
- 👂 Listen: you should hear a click and the motor should start.
If after rebooting the refrigerator makes a series of clicks, but does not start, the problem may be deeper. The electronic module may have been damaged due to a power surge. In such cases, diagnostics of the voltage at the output from the board to the compressor is required.
No Frost system malfunction: heating element and sensors
In refrigerators with a system No Frost or Full No Frost the defrosting process is automated. If the unit does not turn on after manual defrosting, there is a high probability of failure of the elements of the defrosting system. The heating element (heating element) could burn out even before defrosting, and you simply did not notice it until sludge formed.
When turned on, the refrigerator conducts self-diagnosis. If the defrost sensor shows that the evaporator has not warmed up to the required temperature (although the heating element should have done this), or vice versa, shows critical overheating, the cycle does not start. It could also have failed defrost sensor, which is "stuck" in the "defrost" position, preventing the "cool" command from passing to the compressor.
The main signs of a malfunction of the defrost circuit:
- ❄️ On the back wall the freezer remains ice or frost immediately after turning it on.
- 🔇 The compressor tries to start, clicks, but stalls after a few seconds.
- 🌡️ The temperature in the chambers does not drop, although the fan can work.
To check the heating element, you will need a multimeter. It is necessary to ring the spiral for breakage. If the resistance is infinitely high, the heating element must be replaced. This is a common problem in models LG and Whirlpool.
Problems with the starting relay and compressor
If the light is on, it means that voltage is supplied to the network. The next step is the start relay. This device is responsible for starting the compressor engine. During defrosting, moisture could get into the relay, or its resource could simply be exhausted. A burnt-out relay does not supply an impulse to the motor winding, and it remains standing.
The most unpleasant situation is compressor wedge. If you defrosted the refrigerator mechanically (with a scraper, knife) and damaged the wall, or if there is no freon left in the system due to an old leak, the motor may jam. In this case, it hums, heats up, but does not rotate until the thermal protection is triggered.
| Symptom | Probable cause | Solution |
|---|---|---|
| Silence, light lit | Module failure, open circuit | Reboot, check wiring |
| Clicks, but no start | Faulty starting relay | Replacement relay |
| Humming for 5-10 seconds, then silence | Compressor wedge or low voltage | Call a technician, replace the motor |
| Works, but does not cool | Freon leak, breakdown of the heating element | Search for leaks, refueling, repair No Frost |
⚠️ Attention: If the compressor hums and gets very hot (up to 80-90 degrees), immediately disconnect the device from the network. Working in this mode will wind the motor in a matter of minutes, turning the repair into the purchase of a new refrigerator.
The starting relay can be checked visually. Remove the plastic casing from the side of the compressor (after turning off the power!). If traces of burning, melting, or the smell of burnt plastic are visible inside the relay, the part requires replacement. This is a consumable material that is inexpensive.
☑️ Diagnostics before calling a technician
☑️ Diagnostics before calling a technician
☑️ Diagnostics before the call technician
☑️ Diagnostics before calling the technician
Fault of the thermostat and temperature sensors
The thermostat (or electronic temperature sensor) is the “eyes” of the refrigerator. It tells the control module when to turn on the cold. If, after defrosting, the thermostat contacts have oxidized or the device itself has failed, it may constantly “think” that it is already cold in the chamber. As a result, the command to turn on the compressor is simply not received.
In mechanical models, the thermostat has a capillary tube. If during defrosting you pulled the regulator too hard or damaged the tube, the gas could evaporate and the contacts would no longer close. In electronic models Beko or Haier sensors often fail due to power surges when turned on.
You can check a mechanical thermostat by closing its contacts directly (for diagnostics!). If the refrigerator starts when the contacts are closed, it means the thermostat is faulty and requires replacement. However, this should only be done if you have skills in working with electricity.
How to check a temperature sensor with a multimeter?
To check an electronic sensor (thermistor), you need to know its resistance at room temperature (usually about 5-10 kOhm). As your hand warms up, the resistance should drop. If the device shows a break or zero, the sensor is faulty.
Refrigerant leakage and consequences for the compressor
Sometimes the problem is not in the electrics, but in the fact that the refrigerator itself has “defrosted” due to a freon leak before you even started the procedure. You may notice a bulge in the wall or an oily stain on the floor. When such a unit is turned on, the compressor runs empty or does not turn on at all due to protection.
If there is no freon in the system, the pressure does not increase, and the pressure sensors (pressostats) block the operation of the motor. This is a defense mechanism. In this case, simple defrosting and waiting will not help - you need to find the leak, solder and fill the system with refrigerant.
Critical moment: If you hear a hissing sound when you turn it on or see oil under the refrigerator, operating the device is strictly prohibited. Further switching on will lead to combustion of the compressor, since freon also cools the motor.
Frequent questions and answers (FAQ)
How long should the refrigerator dry after defrosting?
The minimum drying time is 12 hours, but a period of 24 hours is considered optimal. If the room has high humidity, it is better to wait two days. Wet contacts are the main reason for startup failure.
Is it possible to speed up startup by turning on maximum cold?
No, this will not help. If the control circuit is broken or the protection has tripped, changing the position of the temperature controller will not make the compressor work. First you need to eliminate the cause of the blockage.
Why does the refrigerator hum loudly after defrosting?
A loud hum may indicate that the compressor is trying to start, but cannot (it is jammed, there is no freon, the relay is faulty). Also, the cause may be a misalignment of the case or foreign objects getting under the fan.
The defrost indicator is on, but the cold does not come out. What to do?
This indicates a failure in the defrost system (No Frost). The heating element, defrost sensor or timer is probably faulty. Diagnostics with a multimeter and replacement of the burnt element are required.