Refrigerator repair. Fault diagnosis

Lecture



The refrigerator is a fairly reliable unit. If the refrigerator did not have manufacturing defects, or you were able to identify them and eliminate them during the warranty period, it will work without repair for at least five to seven years, and individual copies with proper care can last for much longer. In order to repair the refrigerator yourself, you need to submit its device:

1. device refrigerator

A classic refrigerator (without the No Frost system) works as follows:

  1. Motor - compressor (1), sucks gaseous freon from the evaporator, compresses it, and through the filter (6) pushes it into the condenser (7).
  2. In a condenser, freon heated by compression
    cools to room temperature and finally turns into a liquid.
  3. Liquid freon under pressure, through the opening of the capillary (8) enters the internal cavity of the evaporator (5), passes into the gaseous state, as a result, it takes away heat from the walls of the evaporator, and the evaporator, in turn, cools the internal space of the refrigerator.
  4. This process is repeated until
    achieve the temperature of the evaporator walls set by the thermostat (3).
  5. When the required temperature is reached, the thermostat opens the electrical circuit and the compressor stops.
  6. After some time, the temperature in the refrigerator (due to external factors) begins to rise, the thermostat contacts close,
    With the help of the protective start-up relay (2), the electric motor of the motor-compressor is started and the whole cycle is repeated from the beginning (see point 1)

  Refrigerator repair.  Fault diagnosis

1. Motor compressor
2. Protective start relay
3. Thermostat
4. Inner lamp
refrigerator lighting
5. Evaporator
6. Filter drier
7. Capacitor
8. Capillary
9. Lamp switch

Now that we are familiar with the refrigerator, we offer the following sequence of actions:

  1. Try to identify the fault. overwhelmingly, it is easy to follow the instructions for troubleshooting.
  2. If possible, repair it yourself A person familiar with the refrigerator unit and having a minimum set of tools is able to eliminate most of the faults that are not related to the depressurization of the system.
  3. If independent repair is impossible - choose a company, decide on the cost of repair and call the wizard.
  4. At the end of the repair follow the recommendations on the operation of the refrigerator.

2. Fault diagnosis of the refrigerator.

The sequence of actions to identify the failed parts and recommendations for repair. For compressor refrigerators without No Frost system.

  1. Check the voltage in the outlet, it should be in the range of 200-240 Volts, if this is not the case, the refrigerator does not have to work (although it may work for some time, especially older models.)

    All repair work should be carried out with the unplugged and unfrozen fridge!
  2. The fridge does not turn on.

    a) Check whether the light inside the refrigerator burns, if it burned before, and now it does not burn - a fault in the power cord or electrical plug (this is a fairly common fault and you don’t have to call the refrigerator repair technician to fix it).

    b) If the bulb lights up first, you need to check the thermostat:

    - we find two wires suitable for the thermostat, remove them from the terminals and connect them together. If a
    the refrigerator will work after that - we change the thermostat and the repair is finished.

    c) If the thermostat is working properly. Similarly, check the button defrost the refrigerator.

    d) For further diagnostics you will need an ohmmeter. We disconnect and call the start and protective relay (they can be assembled in one case), if we find a break, we replace the defective part.

    e) The motor-compressor motor remains, it is difficult to replace it without the participation of a specialist, but since we got to it, it is worth knowing what exactly the fault is. There are three defects in this unit:

    - winding break;
    - interturn closure winding;
    - short circuit on the motor housing;

    How to identify them in general is understandable: all three contacts of the electric motor should ring each other and not ring with the body. If the resistance between any two contacts is less than 20 ohms, this may indicate an interturn circuit.

    f) If you have carefully done the preceding paragraphs and have not found a malfunction, this most likely indicates oxidation of the contacts in one of the connections of the electrical circuit of the refrigerator. Carefully inspect and clean up all the contact groups that you have analyzed, restore the scheme of the refrigerator in the reverse order - the refrigerator should work.
  3. The refrigerator starts, but turns off after a few seconds.
      Refrigerator repair.  Fault diagnosis


    1 - electric motor
    motor-compressor
    1.1 - working winding
    1.2 - start winding

    3 - thermostat contacts

    10 - defrost button

    11 - protection relay
    11.1 - bimetallic plate
    11.2 - relay contacts

    12 - starting relay
    12.1 - relay coil
    12.2 - relay contacts


    a) Defect of the bimetallic plate 11.1 of the protective relay: we determine the fault and replace the part.
    b) Defect of the coil (or other current sensor) 12.1 start relay: determine the fault and replace the part.
    c) Breakage of the start winding of the electric motor 1.2: we determine the fault and call the refrigerator repair technician to replace the motor-compressor.
  4. The refrigerator works, but does not freeze.

    a) Freon leak: Determined as follows - if the compressor is running and the amount of freon is normal, the condenser should heat up, touch it with your hand (carefully, it can heat up to 70 degrees), if after a long engine run it remains cold, then a depressurization occurs . Disconnect the refrigerator from the network and call the wizard.
    b) Violation of the thermostat adjustment. The device can be temporarily replaced with a known good, if the refrigerator starts working normally - return the faulty thermostat to an adjustment.
    c) Reduced performance of the motor-compressor. This is a difficult to diagnose malfunction, call the wizard.
  5. The refrigerator is slightly freezing

    a) Violation of the thermostat adjustment. The device can be temporarily replaced with a known good, if the refrigerator starts working normally - return the faulty thermostat to an adjustment.
    b) Lost the shape and elasticity of the rubber seal of the refrigerator door. If the door is not closed tightly, warm air will get into the refrigerator, the temperature will not be maintained and the motor-compressor will work with increased load. Carefully inspect the seal, defective - replace. (see also the next item)
    c) The door of the refrigerator led. Adjusting the geometry of the door is carried out by changing the tension of the two diagonal rods that are under the door panel. For details on how to adjust the door, see the elimination of the slots of the doors of refrigerators.
    d) Reduced performance of the motor-compressor. This is a difficult to diagnose malfunction, call the wizard.
  6. Refrigerator freezes hard

    a) If the refrigerator turns off from time to time, but the temperature in it is too low - turn the knob of the thermostat slightly counterclockwise, if that does not help -
    b) the button for quick freezing is forgotten - turn it off.

3. Tips for using the refrigerator

Many malfunctions that subsequently lead to costly repair of the refrigerator result from improper operation of the unit. Here we provide some simple tips:

a) If the refrigerator was turned off for some reason, wait five minutes before turning it on again. This process can be automated using the refrigerator turn-on delay timer.

b) If the refrigerator has been defrosted, do not load it with products before it has run empty for one cycle and does not turn off.

c) Do not set the thermostat pointer farther than the middle of the scale, it will not give a significant gain in temperature, and the engine will work in heavy duty.

d) On some refrigerators in the depth of the refrigerating chamber (on the back wall) there is a "weeping evaporator". Do not lean products against it and do not forget to clean the water outlet located under it.

e) When defrosting the refrigerator, it is unacceptable to pick ice using hard objects, defrost only with warm water.

f) On some refrigerators there is a “quick freeze” button (usually yellow), this button closes the thermostat contacts and the engine runs without shutting down. Do not forget this button down.

g) Do not store vegetable oil in the refrigerator, oil is not required, and the rubber of the refrigerator door seal loses its elasticity.

h) Do not place the refrigerator near the radiators.


Comments


To leave a comment
If you have any suggestion, idea, thanks or comment, feel free to write. We really value feedback and are glad to hear your opinion.
To reply

Diagnostics, maintenance and repair of electronic and radio equipment

Terms: Diagnostics, maintenance and repair of electronic and radio equipment