The situation when, after an expensive repair of household appliances, there is no desired result, causes understandable disappointment and anxiety. Owners often face a problem: they have been replaced, the technician has been paid for, but the unit continues to work non-stop without going into rest mode. This is not just excess noise in the apartment, but also a direct threat to the new motor, which can burn out from overheating without working out even half of the warranty period. compressor, the technician’s work has been paid, but the unit continues to work non-stop without going into rest mode. This is not just extra noise in the apartment, but also a direct threat to the new motor, which can burn out from overheating before even half the warranty period has expired.
There can be many reasons for this behavior of the equipment, and not all of them are related to the defective part itself. Most often, the problem lies in a violation of the work technology, incorrect refrigerant charging, or hidden defects in adjacent components that were not diagnosed before repair. Inverter or a conventional linear motor - the principle of troubleshooting is largely similar, although it has its own technical nuances.
In this article we We will analyze in detail the mechanical, electrical and thermodynamic factors that influence the operating cycle of refrigeration equipment. Understanding these processes will help you intelligently ask questions to the service center or independently identify a critical error if the repair was carried out unskillfully. Remember that Continuous operation is an emergency mode that requires immediate intervention.
Violation of the soldering and vacuum technology of the system
The most common reason for endless operation of the motor is the presence of air or moisture in the cooling circuit. When replacing a compressor, the system must be carefully vacuumed a special pump for a certain time. If the master neglected this stage or carried it out formally, air remained in the tubes.
Air entering the system creates a so-called “air lock”. It does not condense in the condenser as efficiently as freon and creates excess pressure. As a result, the compressor is forced to wear out, trying to push the refrigerant through high resistance, but cannot reach the set evaporation temperature.
⚠️ Attention: The presence of moisture in the system due to poor evacuation leads to the formation of an ice plug in the capillary pipe. This causes cyclic freezing and thawing, but often the motor simply cannot get into mode and hums constantly.
The quality of soldering connections is also critically important. If microscopic shells or oxides have formed at the junction of the copper tube and the steel fitting of the compressor, the throughput is narrowed. Capillary expander is the narrow neck of the system, and any additional resistance before or after it breaks the entire pressure balance.
Incorrect dose of refrigerant: overfilling or underfilling
The amount of freon in the system is not an approximate value, but an exact calculated parameter, depending on the volume of the refrigeration chamber and the power of the compressor. After replacing the motor-compressor, the old mass of refrigerant cannot simply be “added”, since it is no longer known. A complete recharge is required according to the scales.
If the system underfilling has freon, the compressor will work constantly, trying to gain temperature, but the heat transfer efficiency will be extremely low. The motor will be hot, but the evaporator will be only partially cold. In the case overflow liquid freon can enter the compressor cylinder, causing water hammer, but also causing the system to operate without shutting down due to a violation of the thermodynamic cycle.
The exact mass of the charge can only be determined by the factory label, which is usually located on the back wall or inside the camera. Using cylinders with cheap gas or refilling “by eye” based on the temperature to the touch is a sure way to repeated breakdown.
Malfunctions of the thermostat and temperature sensors
They often forget that a new compressor is only the “heart” of the system, but The "brain" is controlled thermostat (thermostat) or an electronic control module. If after replacing the motor the problem remains, it is possible that the sensor is faulty and does not give the command to turn off.
In mechanical thermostats, the calibration could have gone wrong, or the capillary tube of the sensor is not immersed deep enough in the evaporator. In electronic models (No Frost), it could fail NTC sensor, which sends incorrect data about the temperature inside the chamber to the control board.
Checking the thermostat is a relatively simple procedure. In mechanical models, you can temporarily close the contacts going to the thermostat. If the refrigerator starts to shut down (pauses in operation appear), then the problem is in the sensor, and not in the compressor or leak.
Symptoms of a malfunction of the electronic sensor
If the display shows an error (for example, F5 or blinking indicators), and the motor hums incessantly, most likely, the control module receives a signal that the chamber is “warm”, and does not turn off the compressor.
Freon leakage: hidden defect or installation error
The compressor is often replaced precisely because of its combustion, which in 80% of cases is caused by a freon leak. If the technician replaced the motor, but did not find and eliminate the leak, the situation will repeat itself in a month at best, and in the worst case, the refrigerator will not freeze immediately.
The leak may be in the foamed part of the case (the evaporator inside the wall), in the door heating circuit or in the solder joints of the condenser. If there is a fistula, the system cannot build up the pressure necessary to shut down. The compressor runs idle, driving the remaining gas in a circle.
To find leaks, professionals use leak detectors or the method of pressure testing with nitrogen and a soap solution. Ignoring this stage is a sign of low qualification of the master. New oil in the compressor is hygroscopic and will quickly absorb moisture from the air through the leak site, turning into acid.
Table: Diagnosis of the causes of continuous operation
To systematize possible problems, consider the main symptoms and their probable causes in the table below. This will help narrow down your search before calling a specialist.
| Symptom | Probable cause | Test method | Difficulty of repair |
|---|---|---|---|
| Compressor is hot, condenser is warm partially | Insufficient freon or leak | Checking pressure with a pressure gauge | Medium (search for leaks) |
| Strong hum, high outlet temperature | Air lock (poor vacuum) | Visual inspection of the oil, performance analysis | High (needs complete refilling) |
| The refrigerator freezes, but does not turn off | Thermostat or sensor is faulty | Replacing the sensor with a known good one | Low |
| Frost only at the evaporator inlet | Clogged capillary tube or filter | Checking the temperature filter drier | Medium (filter replacement) |
Problems with filter-drier and capillary system
When replacing a compressor, replacement is a mandatory procedure filter drier. This element collects moisture and microscopic debris. If the filter remains old, it could become clogged with decay products of the oil of a burnt engine or simply wear out its service life.
A clogged filter creates resistance to the flow of refrigerant. The suction pressure drops, and the compressor cannot create the pressure difference necessary for normal freon boiling in the evaporator. As a result, the temperature in the chamber does not drop and the cycle is not interrupted.
It is also worth checking the condition of the capillary tube. If soldering was inaccurate, copper scale could get inside, blocking the narrow channel. This requires purging the system with nitrogen under pressure or, in difficult cases, replacing the capillary tube.
⚠️ Attention: Never leave the system open without vacuum or pressure for more than 15-20 minutes. Moisture from the air will instantly be absorbed into the oil and decompose it, which will lead to acidic contamination of the entire system.
Compliance with the power of the new compressor
In pursuit of savings or due to the lack of original spare parts, craftsmen sometimes install compressors with a similar seat, but another power or cooling capacity. This is a gross mistake.
If a motor is installed that is too weak, it will physically not be able to cool the chamber volume to the set temperature in a reasonable time, working non-stop. If the motor is too powerful, the system may not have time to release heat, which will also upset the balance, although this is less common.
It is necessary to check the markings. For example, models Aspera, Secop (Danfoss) or LG have clear indexing. Installing a compressor from a smaller refrigerator will lead to the problem described.
☑️ Checking the correct installation of the compressor
Electric faults and starting equipment
Although replacing the compressor solves the mechanical problem, the electrical circuit also requires attention. A faulty starting relay or capacitor may not ensure proper starting or operation of the windings, although more often this leads to the motor not starting at all or knocking out the machine.
However, if the relay is “stuck” in the closed state, it may theoretically prevent the circuit from breaking, although in modern circuits it is The thermostat responds to shutdown. A more pressing problem is the oxidation of contacts in the power circuit, which causes a voltage drop. The motor hums, but does not develop the required power.
In models with inverter control, the problem may lie within the inverter module. If it does not read the compressor current correctly, it may not command to reduce speed or stop, maintaining maximum performance at all times.
Frequently asked questions (FAQ)
How long should the refrigerator run after replacing the compressor for the first time?
After switching on, the new compressor can operate continuously for 3 to 8 hours until it reaches the initial temperature and freezes the food. However, after reaching operating temperature, it must turn off. If it works for more than 12 hours without pauses, this is a malfunction.
Is it possible to add freon yourself if the refrigerator does not turn off?
It is strictly not recommended. Without vacuuming and scales, you will upset the balance of the system. Adding freon to the system with air or the wrong dosage will kill the compressor. A call from a technician with equipment is required.
Why does the compressor heat up if it is new?
A new motor can heat up more than usual in the first day of operation (up to 70-80 degrees), as parts are being ground in. But if it is so hot that it is impossible to touch it, or works without stopping for days, this is a sign of overload or lack of freon.
Does changing the oil in the compressor affect the problem?
Yes. Modern compressors use synthetic oil (POE), which cannot be mixed with mineral oil. If, when replacing the compressor, a different type of oil entered the system or the old oil was not removed from the condenser, this will cause blockage of the capillary and continuous operation.
What to do if the technician says that “this is how it should be”?
Require a written guarantee for the work performed. If the refrigerator does not turn off for more than a day, this is not the norm. Contact an independent service center for diagnostics (measuring currents, pressures, temperatures) in order to have evidence of poor-quality repairs.