1 Principle of operation and motor designIt is based on the circulation of the refrigerant( freon) in the system. Initially, the refrigerant is a gas, the pressure that creates a compressor, contributes to its release into the condenser. There, the gas is cooled, turns into liquid and flows into the evaporator. When heated, the liquid enters the primary state and repeats the cycle. 
Therefore, if problems arise with compressor operation, it will not create pressure or it will not be enough for normal operation.
The degree of cooling - the temperature in the chamber - regulates the thermostat. From it, the signal goes to the starting relay of the motor, which starts the whole process.
A motor-compressor is located at the rear of the unit housing. It is fixed in a special oil and covered with a protective casing, which you can see in the picture.
The electric motor consists of starting and working windings, as well as a relay.
Three pins are connected to the case, one of which is common. The other two lead to the starting and working winding. In the latest models of refrigerators installed electrical circuit, which can adjust the speed of the engine.
Functional check
For what reasons does the compressor stop working:
- Burned. This happens as a result of a sharp voltage surge and increased load.
- Broken start protection relay.
- Faulty wiring.
It happens that the device is buzzing and working, but there is no cold in the cameras. The cause may be the release of freon gas. Then it is better to contact a specialist who detects a leak and refuel the system.
To find out if the device is working or not, use a multimeter. As soon as you get to the motor, you need to make sure that the case does not penetrate, otherwise it can strike with current. Most often this happens in old refrigerators. Attach the multimeter probes to the body and each contact alternately. If the display shows "∞" - then everything is in order. If numbers appear on the display, the winding is faulty.
In order to perform further diagnostics, you need to remove the casing and open access to the compressor. To do this:
- Disconnect the wiring from the pins.
- Snack motor tubes that connect it to other parts.
Important! Before starting work, find out what type of refrigerant is used in your refrigerator. This gas can be explosive.
- Unscrew the casing fixing bolts and remove from the case.
- Disconnect the relay by unscrewing the screws.
- Now take the device for testing and measure the resistance between the contacts.
- Attach the probes to the right and left output contact. Normally, the resistance will be 30 ohms. The top right shows 15 ohms, and the top left shows 20 ohms.
Based on the model of the engine and the refrigerator itself, the values may vary ± 5 Ω.
- If the readings do not match, the device is faulty. If a break appears somewhere, a conventional or inverter motor must be replaced or repaired.
Compressor passed the test, but the technique does not work? So, proceed to further testing, but not with a tester, but with a pressure gauge.
- You need to measure pressure.
- Connect the hose with the outlet to the pressure fitting.
- Start the engine.
- Measure Your Pressure.
- The indications for a good instrument should be 6 atm and increase. In this case, you need to quickly turn off the pressure gauge, otherwise it will break.
- If the pressure does not reach a bit at 6 atm, such an engine can be installed in medium-sized refrigerators. The readings reach 4-5 atm, which means that the motor can be used in single-chamber refrigerators. Compressor with a pressure of less than 4 atm - non-working.
The health check is passed, but there is no result. The unit still does not turn on. In this case, it is possible to establish the operability of the motor by connecting directly, without a starting relay.
Important! Such work is life threatening. To conduct such a diagnosis can either master or an experienced person.
Connect the motor through the cord according to the scheme:
. As a last resort, it is possible to check whether the motor is working, it is possible through a relay. Perhaps the current does not reach the device.
- Before this, diagnostics was carried out without a relay, now connect it to the motor.
- Run.
- Arm yourself with a tong tester.
- Clamp the power cord that leads to the device.
- Look at the figures: with a power of 140 W, the current should be 1.3 A. With a power of 120 V - 1.1–1.2 A.
Additionally, run a start-up relay diagnostics. His contacts are also measured by a multimeter.
Now you know how to test the motor-compressor with your own hands. See the diagnostic video for credibility:
