Sudden silence in the kitchen after the usual hum or, conversely, a strained hum that turns into a click, always indicates serious problems with the heart of the refrigeration unit. When you are wondering why the refrigerator compressor is jamming, you are already faced with a situation that requires immediate diagnosis, since further operation can lead to a complete replacement of an expensive unit.
The symptoms of a “wedge” are often disguised as other malfunctions, and an inexperienced user may mistakenly blame power surges or poor contact in the socket, wasting precious time. In this article we will analyze in detail the mechanical and electrical causes of rotor blocking, as well as methods that allow you to revive the unit at home or understand that you can’t do without a technician.
Mechanical causes of rotor jamming
The most common and dangerous reason why compressor jamslies in the mechanical wear of friction pairs inside the sealed casing. During long-term operation without proper maintenance or due to manufacturing defects, the crankshaft liners wear out, which leads to runout and eventual scuffing on the cylinder mirror.
When the gaps between the piston and the cylinder become critically small, and the oil loses its lubricating properties or burns out, a dry effect occurs friction. The metal begins to melt and freeze, tightly fixing the piston at the bottom or top dead center, which is why the engine is physically unable to make the first starting revolution.
Another factor is the destruction of the valve group, when fragments of the plate valves fall into the space between the piston and the cylinder. This creates a mechanical barrier that the electric motor is unable to overcome, which is perceived by the user as a dull thud or hum followed by shutdown.
⚠️ Attention: If after clicking the relay you hear a dull knock inside the compressor, do not try to turn on the refrigerator repeatedly. This can completely finish off the engine windings or lead to a breakdown of freon in the system.
In some cases, the cause is not wear, but hydraulic hammercaused by liquid freon or oil entering the cylinder at the time of startup. Liquid, unlike gas, is not compressed, and the piston simply cannot go through the working stroke, resting against the “liquid plug.”
Why does water hammer occur?
Water hammer often occurs after improper transportation of the refrigerator (if it was carried lying down) or when malfunction of the thermostat, when the refrigerant does not have time to evaporate in the evaporator and returns to the compressor in liquid form.
Electrical malfunctions of the starting device
Often a situation where it seems that the compressor is jammedis actually a consequence of the failure of the start-up relay or capacitor. The relay is responsible for sending an impulse to the starting winding to move the rotor from its place, and if this element is burned out, the engine only hums, but does not start.
The starting relay is an electromagnetic or posistor mechanism that degrades over time. The conductivity inside the posistor may be disrupted, and in the electromagnetic relay the contacts may stick or the spring may weaken. Visually, such an element may look intact, but not perform its function.
- 🔌 Burnt posistor: does not provide a short-term increase in current to the starting winding, the rotor stands still.
- ⚡ Contact sticking: the starting winding remains energized for too long, which causes heating and protective shutdown.
- 📉 Voltage sag: if the voltage in the network is below 190 Volts, the starting torque may not be enough to overcome the inertia of the rotor at rest.
Diagnostics of this problem requires a multimeter to test the relay contacts and check the integrity of the windings of the relay itself compressor. If the windings are intact, but the relay does not click or clicks but does not start the motor, the problem lies precisely in the start control circuit.
Problems with the oil and lubrication system
High-quality lubrication is the life of the compressor, and its absence or degradation directly leads to the fact that engine jams. The oil in a sealed circuit circulates along with freon, but over time it oxidizes, especially if there was air or moisture in the system.
Oxidized oil turns into a thick paste-like mass or even solid deposits that clog the thin channels for supplying lubricant to the bearings and piston group. Without an oil wedge, metal parts begin to contact directly, which instantly leads to heating and scuffing.
This problem is especially critical for compressors that have been idle for a long time without operation. The oil drains into the crankcase, and the rubbing surfaces remain dry. When starting for the first time after a long period of inactivity, the risk of jamming is maximum, since the oil does not have time to disperse throughout the system.
| Symptom | Probable cause | Consequences |
|---|---|---|
| Humming without starting | Lack of lubrication | Warming up of windings, wedge risk |
| Dark color of oil | Oxidation, moisture | Clogged capillaries |
| Metal chips | Wear of parts | Complete destruction of the mechanism |
It is important to note that it is impossible to add oil to a running compressor without evacuating the system and replacing the filter-drier. An attempt to simply pour oil through a process pipe without a proper procedure often leads to the formation of an “oil plug” in the circuit, which impairs cooling performance.
☑️ Diagnostics of the oil system
The influence of temperature and operating conditions
External factors play a huge role in the durability of the compressor, and often the answer to the question is why refrigerator compressor is jammedlies in incorrect operating conditions. Operation at temperatures below +10°C or above +35°C creates extreme loads on the mechanism.
At low temperatures, the oil thickens, becoming like tar, which dramatically increases resistance at start-up. The motor tries to turn the shaft, but the viscous oil acts as a brake, causing overheating of the windings and tripping of the thermal protection.
⚠️ Attention: Installing the refrigerator close to the wall or in a niche without clearance for ventilation leads to overheating of the compressor. Thermal expansion of parts can change the gaps and cause a wedge.
High ambient temperatures are also dangerous: the compressor works non-stop, trying to gain temperature, and does not have time to cool down. Constant overheating leads to deformation of the cylinder body and piston, which ultimately ends in their biting.
In addition, frequent switching on and off (short cycles) does not allow the oil to return to the crankcase and create the desired film. If you often open the door or load warm food, the compressor runs jerkily, which accelerates wear.
Diagnostics: buzzes, clicks, but does not start
To accurately determine whether the compressor is jammed or the problem is in the electrical system, it is necessary to carry out an initial diagnosis. The first thing you need to do is listen to the sounds: a steady hum, turning into a click and silence, usually indicates an attempt to start and a protective shutdown.
If you hear a quiet hum when you turn it on, and after a few seconds there is a loud click and everything goes quiet - this is a classic picture of the operation of a thermal relay. It sees that the current is rising (the rotor is not spinning) and breaks the circuit to prevent a fire.
For a deeper check, you need to remove the starting relay and check the resistance of the windings with a multimeter. The normal resistance of the starting winding is usually higher than the working one. If the device shows an open circuit or, conversely, a short circuit (close to zero), the compressor requires replacement.
However, if the winding resistance is normal and the relay is working properly, but the shaft does not rotate, the probability of a mechanical wedge is 90%. In this case, you can try the “wedging” method, but it requires caution and an understanding of the risks.
Methods for compressor wedging
There is a popular, but risky method, sometimes allowing you to resuscitate a jammed unit. Its essence is to apply voltage to the working winding, bypassing the starting device, sometimes with a short-term increase in voltage to create a powerful magnetic pulse.
Attention: this method is applicable only if you are sure of the integrity of the windings and the absence of a short circuit. Voltage is applied to the compressor housing, and at the moment of switching on, a characteristic click is often heard - the rotor breaks away.
Connection diagram for wedging:Phase -> Working winding
Zero -> Common winding
(The starting winding is not directly involved)
Another method is tapping. While the compressor is under voltage (or immediately after trying to turn it on), you need to gently but firmly tap the compressor housing with a rubber mallet at different points. Vibration can help destroy the oxide film or move a jammed part.
If these methods do not help, or the compressor starts, but immediately hums and turns off, then the damage to the mechanical part is irreversible. In this case, only replacing the compressor with a new one will help, since it is impossible to open the sealed casing and repair the crank mechanism at home.
⚠️ Attention: The wedging method with increased voltage is dangerous due to insulation breakdown. Use it only as a last resort, when replacing the compressor is not economically feasible and you are aware of the risk of final failure of the equipment.
When it is necessary to replace the compressor
If the diagnostics showed an interturn short circuit in the windings, a breakdown on the housing or deep mechanical damage, the only option is replacement. Modern compressors are often beyond repair, and their replacement is a standard service procedure.
Replacement requires not only the installation of a new unit, but also a complete evacuation of the system, replacement of the filter drier and charging the exact amount of refrigerant. Errors at any stage will lead to rapid failure of the new compressor.
- 🛠️ Dismantling: cutting off old tubes, removing the faulty compressor.
- 🧹 Purge: cleaning the circuit of oil combustion products and nitrogen contamination.
- 🔧 Installation: installation of a new compressor and filter, soldering of connections.
- ❄️ Refilling: vacuuming and starting freon by scale.
The cost of such a procedure consists of the price of the compressor itself and the work of the technician. Often for old refrigerators this amount can be a significant part of the cost of a new device, so the feasibility of repairs must be assessed individually.
Is it possible to install a more powerful compressor?
Theoretically it is possible, but this requires reconfiguring the thermostat and can lead to improper operation of the refrigerator. It is better to use an original analogue or a complete structural analogue in terms of power and refrigerant.
Why does the compressor heat up but not cool?
If the compressor is working (humming), getting very hot, but there is no cold, most likely there is a break in the pipeline inside the system or a freon leak. The compressor wastes gas without creating the required pressure, or operates under vacuum. The capillary tube may also become clogged.
How much does it cost to replace a jammed compressor?
The price depends on the model of the refrigerator and the type of compressor (inverter or conventional). On average, a technician’s work together with spare parts can cost from 50% to 80% of the cost of a new budget-class refrigerator.
Is it possible to repair a compressor with your own hands?
It is impossible to properly repair a sealed compressor at home. This requires special equipment for welding, vacuuming and precision filling. Independent attempts often lead to complete failure of the equipment.
How to extend the life of a compressor?
Do not place the refrigerator near the radiator, do not load hot foods, let it settle after transportation for at least 4-6 hours and defrost regularly (if it is not No Frost). This will reduce the load on the motor.