Completing work to restore the functionality of refrigeration equipment often does not bring the expected peace of mind if the unit continues to hum for hours. Owners who have just paid for the services of a technician or replaced parts themselves begin to panic when they hear the continuous hum of the engine. A reasonable question arises: is long-term operation the norm or is urgent intervention required?
The situation when compressor does not go into rest mode can be either a normal process of entering the mode or a sign of an installation error. The time required to stabilize the temperature directly depends on the volume of the chamber, the type of refrigerant and the complexity of the work performed. Understanding the physical processes within the system will help avoid false service calls.
It is important to consider that the initial start-up always takes longer than a normal refrigeration cycle. If you changed the door seal or simply defrosted the unit, it will work longer. However, after replacing the motor or refilling with freon, the time frame may differ significantly from the usual values.
Physics of the process: why the refrigerator works without stopping
The principle of operation of the refrigeration circuit is based on the circulation of the refrigerant, which takes heat from the internal space and releases it to the external environment. After downtime or repairs, the temperature of the walls of the chambers and products is significantly higher than the target values. Thermostat or the electronic control module detects the high temperature and gives a command for continuous operation until the specified parameters are reached.
In normal mode, the cooling cycle consists of work and rest. However, when starting for the first time, the rest phase may be completely absent. This is due to the fact that the heat capacity of food and metal requires a long time to remove energy. The compressor is forced to work at its limit to compensate for thermal shock.
Particular attention should be paid to the type of refrigerant. Modern models using R600a (isobutane) often have longer operating cycles compared to older models using R134a. This is due to the lower operating pressure and the characteristics of heat exchange in the evaporator.
The duration of this stage depends on many factors, including the ambient temperature in the room. If the room is hot, heat exchange in the condenser (grid at the back) is difficult, which forces the system to work harder and longer.
Standard indicators for operating time after different types of repairs
The answer to the question of how long it takes for the refrigerator to turn off cannot be given with one number for all cases. The time to enter the mode varies depending on what kind of manipulations were carried out with the equipment. It is critical to distinguish between cosmetic repairs and tampering with the sealed circuit.
If the thermostat start relay was replaced, the refrigerator should begin to cycle on and off almost immediately as soon as the internal temperature drops to the set temperature. This usually takes from 40 minutes to 2 hours, depending on the load of the chambers.
A completely different picture is observed after replacing the compressor or eliminating a freon leak. In such cases, the system is completely empty or filled with air that needs to be displaced. The primary cooling process can take up to 24 hours, especially in models with a system No Frost, where you need to cool not only the food, but also the massive evaporator hidden behind a plastic panel.
It is worth noting that in hot weather or when the chambers are fully loaded with warm products, the operating time can increase by one and a half times. You should not expect an instant result if you loaded a three-liter pot of soup into the unit that was just turned on.
Table: Approximate operating time before the first shutdown
For the convenience of assessing the situation, we suggest that you familiarize yourself with the summary data. They will help you determine whether the behavior of your equipment is abnormal.
| Type of work performed | Expected operating time before the 1st shutdown | Influence factors |
|---|---|---|
| Replacement of the door seal | 2 – 4 hours | Seal tightness, room temperature |
| Replacing the thermostat / sensor | 1 – 3 hours | Calibrating a new sensor, initial temperature |
| Refrigerant charging (freon) | 6 - 12 hours | Freon type, system volume, presence of No Frost |
| Replacement of the compressor | 12 - 24 hours | Vacuum quality, cleanliness systems |
| Defrost (scheduled) | 3 - 6 hours | Volume of defrosted moisture, loading with products |
The data in the table are averaged. Actual indicators may differ depending on the model Indesit, Atlant or Liebherr, since the design features of heat exchangers vary among manufacturers.
If your case falls within the specified framework, most likely the equipment is working normally. The alarm should be raised only when these standards are significantly exceeded without a visible decrease in the temperature inside.
Critical installation errors that interfere with shutdown
There are situations when the refrigerator hums for days not because of the physics of the process, but due to the fault of the technician or incorrect installation. One of the most common reasons is insufficient vacuum system before refueling.
If there is air or moisture left in the circuit, they create a so-called “air lock”. This sharply increases the pressure in the system, the compressor works overload, but does not cool effectively. Moisture can freeze in the capillary tube, completely blocking the circulation of the refrigerant.
⚠️ Attention: If after replacing the compressor the unit operates for more than 12 hours and does not cool (or cools weakly), and the condenser (grid at the back) remains barely warm or cold, immediately turn off the device. This is a sign of capillary blockage or air lock.
Another common mistake is incorrect refrigerant dosage. A lack of freon leads to the fact that the compressor cannot gain the required pressure and works continuously, trying to compensate for the lack of refrigerant. Excess freon is also dangerous: liquid refrigerant can enter the compressor, causing water hammer.
Do not forget about trivial things. After the repair, the repairman might have forgotten to close the door tightly or not fully latched the seal. Even a gap will lead to a constant flow of warm air, and the sensors will require continuous operation of the motor.
☑️ Checking the quality of installation
Defects in the installed spare parts are also possible. The new thermostat may be faulty initially, sending false signals about high temperatures.
Diagnostics: how to understand that it’s time to sound the alarm
How can an ordinary user distinguish a long rise in temperature from a breakdown? There are several indirect signs that indicate a malfunction. First of all, assess the temperature inside the chambers. If more than 10 hours have passed and the refrigerator compartment is still warm (above +10°C), this is a bad sign.
Pay attention to the nature of the condenser operation. Normally, the side walls or rear grill should be hot (up to 50-60°C). If the compressor is running, but the grate is cold, there is no circulation. If the grate is hot to the point where it hurts to touch, but there is no cold, there may be air in the system or the filter drier is clogged.
Listen to the sounds. Normal operation is accompanied by a monotonous hum. If you hear gurgling, hissing, or intermittent clicking sounds, this may indicate problems with freon circulation. It is especially dangerous if the compressor is running, but after a while it turns off spontaneously with a loud click and a thermal crackling sound - this is when the thermal overheating protection relay is triggered.
How to check the thermostat without instruments?
The lowered end of the thermostat capillary can be gently warmed in the palms of your hands. If the compressor turns off while the refrigerator is running, try warming this area. If the engine does not start after 2-3 minutes, the thermostat may be faulty or its range may be off.
It is also important to check whether the food is frozen. If the refrigerator works without stopping for several days, and milk or herbs freeze in the refrigeration compartment, it means that the adjustment is broken or the defrost sensor has failed (in No Frost systems).
Specifics of operation of refrigerators with No Frost and inverter models
Owners of equipment with the system No Frost often face more long work cycles. In such models, the evaporator is hidden deep inside the housing, and the air flow must drive the cold through the entire chamber. Until the evaporator itself and the air channels cool down, the sensor will not give a shutdown command.
In addition, in systems No Frost the defrost timer is critically important. If after repair the settings are lost or the timer is stuck in the "cooling" mode, the refrigerator will work forever until it becomes covered in ice and stops on its own due to the fan being blocked.
Inverter compressors, which are becoming standard in models LG, Samsung i Bosch, behave differently than the old linear ones motors. They may not turn off at all! Their task is to maintain temperature while operating at low speeds. Therefore, the absence of a characteristic shutdown click and the transition to a barely audible hum is the norm for them.
⚠️ Attention: In inverter models, the absence of pauses in operation is not a breakdown if a stable temperature is maintained inside. You should worry if the motor hums at full speed for days.
Inverter systems are characterized by a smooth increase in speed. If you hear sudden starts and stops, there may be a problem in the control module or the compressor itself.
What to do if the refrigerator does not turn off: algorithm of actions
If you find that the continuous operation time has exceeded all reasonable limits, do not immediately disassemble the unit. Follow the step-by-step algorithm to localize the problem.
First, carry out a visual inspection and measurements. Make sure the door closes tightly and the seal is clean and not deformed. Check whether the refrigerator is too close to the wall or radiator - overheating of the capacitor also causes prolonged operation.
Try to forcefully disconnect the refrigerator from the network for 15-20 minutes. Allow the system to “rest” and the pressures to equalize. After switching on, note the time. If the situation repeats itself, and the engine again runs for hours without a break, and the cold does not build up, there is a technical problem.
In the case where the repair was carried out recently (less than a week ago), and you observe the symptoms described, the most reasonable step would be to contact the contractor works A warranty case is not only a breakdown, but also poor-quality installation.
If you replaced the part yourself, double-check the compliance of the spare parts with the model of your refrigerator. Installing a thermostat with other parameters (for example, for a freezer instead of a refrigerator) will lead to eternal operation or a complete absence of cold.
Why does the refrigerator turn off, but does not turn on again?
If the refrigerator has completed a cycle, turned off, but no longer starts, the compressor's thermal protection may have tripped due to overheating, or it is faulty start relay. The cause may also be a burnt-out thermostat, which has broken the circuit and does not close it when the temperature rises.
Is it normal for the refrigerator to hum louder after repair?
In the first hours of operation after charging with freon, the noise may be slightly higher than usual due to the active circulation of the oil and gas mixture. However, a strong knock, clanging or high-pitched whistle is not the norm and requires checking the compressor mounts and the condition of the pipelines.
Can a new part be defective?
Yes, the probability of a factory spare part being defective exists, although it is low. Defects are especially common in Chinese analogues of thermostats and starting relays. If a new part is installed, but the behavior of the equipment has not changed, it is worth checking it with a multimeter.
Does the number of products affect the operating time?
Absolutely. An empty refrigerator cools down faster. If you loaded the chambers with room temperature products immediately after turning them on, the operating time before the first shutdown may increase by 2-3 times, since the heat capacity of the products is very high.