The situation when the refrigerator stops freezing, and it compressor only hums or clicks, but does not start, is familiar to many owners of household appliances. In most cases, this indicates that the engine's piston group is seized and the engine is unable to overcome the resistance to start rotating. This occurs due to long periods of downtime, poor quality oil or mechanical wear of parts. If you decide to act on your own, it is important to understand that you are working with high voltage and flammable gases, therefore lack of tightness of the system when opening the circuit will lead to instant release of freon moisture gets inside.
Before taking radical measures, it is necessary to carry out initial diagnostics in order to exclude simpler faults, such as a breakdown of the start relay or broken windings. Often, owners mistake a burnt out motor-compressor for a wedge, although the problem may lie in the control system. In this article, we will analyze in detail the methods that allow us to reanimate the unit, assess the risks and determine in which cases refrigeration circuit it is no longer possible to restore without replacing the unit.
Primary diagnostics and checking the electrical part
The first step should always be Become checking the integrity of the motor windings, since starting a motor with an interturn short circuit is strictly prohibited. To do this, you will need a multimeter set to resistance measurement mode. The start relay and protective cover must be removed to gain access to the three compressor contacts. By measuring the resistance between pairs of contacts, you must obtain specific values: between the working and starting windings, the sum should be equal to the resistance between the working and starting contacts.
If the device shows infinity or, conversely, zero, this indicates that electrical circuit is broken, and mechanical methods will no longer help here. It is also important to check whether the winding is breaking through the housing, which is a direct sign of the need to replace the unit. Only after making sure that the electrics are in good working order can you proceed to wedging attempts.
- 🔌 Check the integrity of the wires going from the thermostat to the compressor.
- 📉 Measure the resistance of the windings: the norm is usually from 10 to 30 Ohms for working and 30-50 Ohms for the starting relay.
- 🛑 Make sure that the starting relay has no visible damage or carbon deposits on the contacts.
⚠️ Attention: If a breakdown is detected during testing, further operation or attempts to start can lead to electric shock. Stop work immediately.
Method of applying increased voltage to start
One of the common methods of resuscitation is to briefly apply voltage directly to the working winding, bypassing the standard starting relay. This method is based on creating a powerful starting impulse that can rip the pistons out of place. However, there is a high risk here: if the motor does not start in 2-3 seconds, the windings may burn out due to lack of protection against overheating.
To implement this method, a wire with a plug is used, which is connected directly to the motor contacts. It is important to observe polarity and use wires of sufficient cross-section so that they do not melt from the inrush current. If you hear a characteristic click and hum, but the shaft does not turn, the procedure can be repeated, but no more than 3-4 times at intervals for cooling.
The effectiveness of this method depends on the degree of jamming. If the reason lies in thickened oil or slight sticking of parts, a current pulse often helps. In case of serious mechanical damage to the piston group, this method will only finish off the engine, turning it into scrap metal.
Warming the compressor housing with a fan heater
Often the reason for the inability to start is frozen or thickened oil, especially if the refrigerator has been standing in a cold room for a long time. In such a situation, an effective method is to heat the lower part of the unit where the motor is located. Heat dilutes the lubricant and expands metal parts, which can free jammed components.
For this procedure, it is best to use a hair dryer or a powerful fan heater, directing a stream of hot air to the bottom of the compressor. The heating temperature should not exceed 100-120 degrees Celsius, so as not to damage the varnish coating of the windings or plastic elements nearby. The process may take from 15 to 40 minutes, after which you should try to start the engine.
After warming up, it is necessary to quickly apply voltage to the starting winding, before the motor has cooled down. If you hear that the shaft begins to turn and there is a sound of operation, then the method has worked. At this moment, it is important that the cooling system works correctly, otherwise overheating will recur.
Using freon impact for wedging
The most professional, but also technically complex method is to supply freon under pressure directly into the discharge tube. The gas pressure inside the cylinders can overcome the friction force and rotate the shaft. This requires a cylinder with nitrogen or freon, a reducer and a plug hose, which is sealed onto the tube.
The essence of the method is to create a short-term pressure surge that acts on the pistons on the discharge side. This often helps when the jam is caused by water hammer or an oil film wedge. It is important not to overdo it with pressure so as not to damage the valves or rupture the thin walls of the tubes.
| Method of influence | Required equipment | Efficiency | Risk of damage |
|---|---|---|---|
| Increased voltage | Wires, plug | Low/Medium | High (winding combustion) |
| Thermal heating | Hair dryer, fan heater | Average | Low |
| Gas pressure | Cylinder, reducer, hose | High | Medium (rupture of tubes) |
| Mechanical turning | Shaft tool | Very low | High (depressurization) |
After successful starting in this way, the refrigerator can operate for a long time. However, it should be understood that this is a temporary measure, and the resource compressor has already been exhausted. In the near future, you should plan to purchase new equipment or replace a unit.
Mechanical rotation of the shaft
There is an opinion that the compressor shaft can be rotated manually through a technological hole or by removing the casing. However, in modern sealed units this is almost impossible to do without completely disassembling the housing, which will break the vacuum and require complex welding. Attempts to rotate the shaft through the fittings often lead to their breakage.
If you managed to gain access to the end of the shaft (which is rare in everyday conditions), rotation should be made only in the direction of the working stroke, usually clockwise. Sudden jerks can break the connecting rod or piston. This method is more suitable for open industrial-type compressors than for domestic refrigeration units.
Why can’t you disassemble a hermetically sealed compressor?
The hermetically sealed housing is welded at the factory. Opening it requires special skills, equipment for inert gas welding and precise balancing. At home, it is almost impossible to restore tightness and vacuum, so such compressors are considered disposable.
If you do not have the skills of a refrigeration mechanic and do not have special tools, it is better to refrain from mechanical intervention. The risk of permanently damaging the equipment here is close to 100%.
Replacing the starting relay as an alternative to repair
Before trying to revive the motor itself, it is worth ruling out a malfunction of the starting device. Often it is a burnt posistor pellet or sticking relay contacts that imitates a compressor wedge. Replacing this element is inexpensive and does not require breaking the tightness of the circuit.
To replace, you need to remove the old relay, remember the position of the contacts and install a new one that matches the model of your compressor. There is usually a marking on the relay body that allows you to select an analogue. If, after replacing the relay, the motor hums but does not start, then the problem is really in the engine mechanics.
⚠️ Attention: Installing a relay from a different compressor model can lead to incorrect operation of the starting winding and rapid failure of the motor. Use only compatible parts.
☑️ Check before starting
Frequently asked questions and answers
Is it possible to restore the compressor permanently after wedging?
No, wedging is a symptom of critical wear or damage. Even if it is possible to start the engine, its resource will be extremely limited, and a second wedge will occur in the near future.
How much does it cost to replace a compressor in the service?
The cost consists of the price of a new unit, the cost of resoldering the pipes, evacuation of the system and refilling with freon. This usually makes up a significant portion of the cost of a new refrigerator.
Is it dangerous to use the high voltage method?
Yes, it is dangerous. There is a risk of wiring fire, electric shock, or oil vapor explosion if there is a short circuit inside. Safety precautions are required.
Why does the compressor hum but does not start?
The hum means that current is supplied to the windings and a magnetic field is created, but mechanical resistance (wedge) does not allow the shaft to rotate. This may also be a sign of a faulty start relay.