The situation when the refrigerator does not turn off immediately after an expensive compressor replacement causes panic in any owner. It would seem that the master has completed the work, the equipment should work like new, but instead of the expected silence and cyclicity, you hear the continuous hum of the engine. This does not always mean that the repair was carried out poorly, but the problem cannot be ignored, since continuous operation can quickly damage a new expensive unit.
There can be several reasons for this behavior of the equipment: from the banal entry of air into the system to difficulties with setting the thermostat or refrigerant leakage. Repair specialists note that in most cases the problem lies not in the compressor itself, but in accompanying system elements or installation errors. It is important not to panic, but to consistently analyze the symptoms in order to understand whether the situation requires calling the technician again or adjusting the settings yourself.
In this article we will analyze in detail why The refrigerator runs non-stop, what parameters need to be checked first and when to sound the alarm. Understanding the physical processes occurring inside the refrigeration circuit will help you correctly assess the quality of the repair performed and avoid repeated breakdowns.
Air in the cooling system: the main reason for the lack of shutdown
One of the most common reasons why the refrigerator does not turn off after replacing the motor, there is air in the system. When carrying out work on vacuuming the circuit, it is necessary to strictly follow the technology. If the technician was in a hurry or used a faulty vacuum pump, microscopic air bubbles remain in the tubes.
The problem is that air, unlike freon, does not condense at operating temperatures. It accumulates in the condenser (the grill at the back of the refrigerator), creating the so-called air lock. This leads to a sharp increase in pressure in the system. The compressor is forced to work with overload, trying to push the refrigerant, but due to high pressure, the sensors do not give a command to stop, or the temperature inside the chambers simply does not have time to drop to the set one.
⚠️ Attention: Operating the refrigerator with air in the system leads to overheating of the compressor. The motor can burn out after several days of continuous operation under load, which is often not recognized as a warranty case.
How to determine the presence of air? Pay attention to the capacitor. If the top of the grate is very hot and the bottom is cold, or if you hear gurgling or hissing, this is a sure sign of airing. Also on evaporator an ice coat may form unevenly.
- 🌡️ The pressure in the system exceeds the norm, the compressor hums with a strained sound.
- ❄️ The refrigerator compartment does not freeze properly, despite the motor running.
- 🔥 The condenser heats up unevenly: the top is hot, the bottom is cold.
To fix this problem, you need to call the technician again. It is necessary to bleed off the freon, re-evacuate the system for a long time (at least 30-40 minutes) and fill the refrigerator with a new portion of refrigerant strictly by weight.
Incorrect charging with freon: overfilling or underfilling
The amount of refrigerant in the system is a critical parameter. After replacement compressor the system is charged again, and here a mistake can be made. If more freon is filled than normal (overfilling), liquid refrigerant can enter the compressor, causing a water hammer, or simply create excess pressure, which disrupts the cooling cycle.
In case of underfilling, the situation is even more obvious: the refrigerator does not turn off, because the temperature sensors simply do not record the achievement of the desired minimum. The engine circulates the remaining gas in a circle, but there is not enough cold. The system operates in “perpetual motion” mode, trying to compensate for the lack of working fluid.
Symptoms of improper charging are often similar to those of an air lock, but there are also differences. If the compressor is underfilled, it may be colder than usual, and the evaporator is only partially covered with frost. When overflowing, freezing of the tube coming out of the compressor and severe freezing of ice in the freezer are often observed.
It is important to understand that it is impossible to independently adjust the amount of freon without a pressure gauge station and scales. Attempts to “bleed off excess” through a puncture will lead to a complete leak and moisture entering the system.
Problems with the thermostat and temperature sensors
Often when replacing a compressor, technicians forget or do not consider it necessary to check the serviceability of thermostat (thermostat). If you replaced the motor on an old refrigerator, there is a high probability that the thermostat has already exhausted its service life. Its contacts could “stick” in the “on” position, and now it physically cannot break the electrical circuit.
In modern models with electronic control (No Frost, Full No Frost), the role of a mechanical thermostat is performed by temperature sensors (NTC). If the sensor wire is damaged during repairs or fails, the control module receives incorrect data. Thinking that the chamber is warm, the “brain” of the refrigerator gives the command to the compressor to work continuously.
Diagnostics of the thermostat is simple: if it is a mechanical model, you can try to gently tap the regulator or temporarily close/open its contacts (for professionals). If the compressor stops after opening the contacts, the problem is in the thermostat. Electronic systems require testing the sensors with a multimeter.
Replacing the thermostat is a quick and inexpensive procedure, but necessary. Ignoring this detail will lead to the fact that the new compressor will wear out, and the food in the refrigerator may freeze.
Installation errors and system tightness
The quality of pipe soldering is the foundation for the long service life of the refrigerator. If, when replacing the compressor, errors were made in soldering, solder could enter the system, blocking the capillary tube, or a microcrack could form. Clogged capillary tube is a common reason why the refrigerator does not turn off.
If clogged, freon does not circulate ok. The pressure at the outlet of the compressor increases, and at the inlet it decreases. The compressor works, but there is no cold. The thermostat “sees” the warm chamber and does not give the command to rest. This is a classic situation when the refrigerator hums, but does not freeze.
It is also worth checking the tightness of the connections. If there is a fistula somewhere, the freon will slowly leave. At first, the refrigerator will simply take longer to reach the temperature, and then it will start working without stopping. Over time, it will stop freezing at all.
☑️ Checking the quality of installation
Particular attention should be paid to the filter drier. When replacing a compressor, it is always replaced. If the old filter remains, it could be saturated with moisture and now lets water into the system, which freezes in the capillary, creating an ice plug.
The influence of operating mode and operating conditions
The reason is not always a breakdown. Sometimes the refrigerator does not turn off due to external factors that worsened after the repair. For example, if the refrigerator is located close to the wall, the radiator cannot efficiently transfer heat. After replacing the compressor, which may have slightly different heat transfer characteristics, this becomes critical.
It is also worth checking the rubber seals on the doors. If they do not fit tightly, warm air constantly enters the chamber. The compressor tries to cool this flow and does not turn off. After the repair, the repairman may not have closed the door tightly or damaged the seal during installation.
During the hot season, the load on the equipment increases. If the room is +30°C, the refrigerator can work almost without interruption, and this is normal for maintaining the temperature. However, if at night, when the room is cool, the motor continues to hum, this is a malfunction.
Fault diagnosis table
For the convenience of analyzing the situation, we will summarize the main symptoms and their possible causes in a table. This will help you formulate the problem when talking to the service center.
| Symptom | Probable cause | Associated symptoms | Urgency of repair |
|---|---|---|---|
| The compressor is hot, hums, no cold | Air in the system or clogged | The condenser is hot only at the top | High (risk of combustion) |
| The motor is cold, runs constantly | Insufficient freon or leak | The evaporator is partially covered with frost | Average |
| The refrigerator freezes too much | Thermostat is faulty | The food is frozen, there is ice in the chamber | Medium |
| Gurgling is heard, the motor does not turn off | Airing of the system | Uneven heating radiator | High |
When you need to call the technician again
If more than 6-8 hours have passed after replacing the compressor, and the refrigerator has not returned to normal mode (it has not turned off for at least 15-20 minutes), you need to act. For the first few hours after switching on, the equipment can work continuously, gaining the initial temperature, especially if the chambers were empty and warm.
⚠️ Attention: Do not wait for days! If a new compressor operates abnormally (with air, without oil, or clogged), it can burn out within 24-48 hours. Warranties in such cases are often void.
Be sure to contact the service if:
- 🔊 Unnatural noise, knocking or strong vibration appears.
- 🌡️ The temperature in the refrigerator compartment is above +10°C after 12 hours of operation.
- 💧 Traces of oil are noticeable on the floor or at the place where the pipes are soldered.
When contacting the service center, request repeated diagnostics using pressure gauges. The technician must check the suction and discharge pressure, as well as the current consumption of the compressor. Only these parameters give an accurate picture of what is happening inside the system.
Is it possible to add freon if it is not enough?
Yes, but only if the brand of refrigerant is known and after checking the system for leaks. You cannot simply “add gas” without evacuation - this will disrupt the operation of the mixture and can damage the compressor.
Prevention of repeated breakdowns
In order for a new compressor to serve for a long time, it is important to provide it with the right conditions. After eliminating the problem, let the refrigerator run idle (without food) for at least a day. This will allow the system to stabilize and you to ensure that the on and off cycles are correct.
Regularly clean the capacitor of dust. A dirty grill at the back of the refrigerator is one of the main reasons for overheating and continuous operation of the motor. Also, do not put hot foods inside and do not keep the door open longer than necessary.
Remember that refrigerator is a complex unit, and replacing the “heart” of the system requires high qualifications. Entrust repairs only to trusted specialists with equipment, and then your equipment will last for many more years.
How long should the refrigerator work after replacing the compressor before the first shutdown?
Normally, the first cycle can last from 2 to 8 hours, depending on the volume of the chambers and the temperature in indoors. If after 10-12 hours of continuous operation there is no shutdown, this is a cause for concern.
Can an old thermostat ruin a new compressor?
Yes, if the thermostat is stuck and does not turn off the motor, the compressor will wear out, which will significantly reduce its life. When replacing the motor, it is recommended to change the thermostat.
Why does the refrigerator hum loudly after repair?
A loud hum may indicate incorrect installation (casing vibration), problems with the compressor mounts, or that the motor is operating under high load due to air in the system or blockage.
What to do if the master claims that “this is how it should be”?
Ask for measurements of pressure and current. A normal refrigerator cycles. If there are no arguments, contact an independent expert or other service center to check.