Domestic Refrigeration

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Domestic Refrigeration

  1. 1. Domestic Refrigerators Common Faults
  2. 2. Introduction <ul><li>The following presentation was made to assist 1st year apprentices with working on domestic refrigerators/freezers </li></ul><ul><li>It is important to note that around 90% of service calls to domestic refrigerators/freezers are related to electrical problems </li></ul><ul><li>The following presentation will cover 4 common electrical faults with domestic refrigerators/freezers </li></ul>
  3. 3. Faulty Thermostat <ul><li>The first fault we will cover is a service call to a domestic refrigerator; the customer is complaining his fridge is freezing all of his food. </li></ul>
  4. 4. Faulty Thermostat <ul><li>This is a common problem with older fridges and the first thing that you want to look at is the thermostat. </li></ul>
  5. 5. Faulty Thermostat <ul><li>Check the compressor and you will find that it is running. </li></ul>
  6. 6. Faulty Thermostat <ul><li>Then wind the thermostat to setting 1. </li></ul>
  7. 7. Faulty Thermostat <ul><li>Then check to see if the compressor has cycled off. </li></ul><ul><li>You will find that it is still running. </li></ul>
  8. 8. Faulty Thermostat <ul><li>Disconnect power. </li></ul>
  9. 9. Faulty Thermostat <ul><li>Locate thermostat housing and remove the thermostat. </li></ul>
  10. 10. Faulty Thermostat <ul><li>Disconnect thermostat wires. </li></ul>
  11. 11. Faulty Thermostat <ul><li>Then test with your multi meter on the ohms setting, you will find that the thermostat still has resistance in the off position. </li></ul><ul><li>This indicates the thermostat contacts are welded together. </li></ul>
  12. 12. Faulty Compressor <ul><li>The second fault we will cover is a service call to a domestic refrigerator; the customer is complaining his fridge is not running </li></ul>
  13. 13. Faulty Compressor <ul><li>The first thing you want to look at is the compressor. </li></ul><ul><li>You find that the compressor is not running, there can be a number of reasons for this, but we will look at just one of them. </li></ul>
  14. 14. Faulty Compressor <ul><li>Disconnect power. </li></ul>
  15. 15. Faulty Compressor <ul><li>Take your multi meter and check the resistance of the over load switch. </li></ul>
  16. 16. Faulty Compressor <ul><li>In this instance you’ll find that the overload switch is open circuited. </li></ul><ul><li>If you find yourself in this situation, it is important to find the cause of the over load switch being open circuited as you can damage the new over load switch if there is another problem. </li></ul>
  17. 17. Faulty Compressor <ul><li>This is where you’ll need to test the compressor windings to determine whether the compressor is pulling too much current thus blowing the over load switch. </li></ul>
  18. 18. Faulty Compressor <ul><li>Check readings between Common and Start. </li></ul>
  19. 19. Faulty Compressor <ul><li>Check readings between Common and Run. </li></ul>
  20. 20. Faulty Compressor <ul><li>Check readings between Run and Start. </li></ul><ul><li>A check of the resistance windings show the start winding has a lower resistance value than required indicating that the winding insulation is breaking down causing it to draw too much current, and this is the reason that the over load switch is blowing on start up. </li></ul>
  21. 21. Faulty Heater <ul><li>The third fault we will cover is a service call to a domestic refrigerator; the customer is complaining his fridge is blowing fuses in the meter box </li></ul>
  22. 22. Faulty Heater <ul><li>There could be a number of reasons why this could be happening, but we will be focusing on just one. </li></ul><ul><li>Locate your heater which will be found near the evaporator coil. </li></ul>
  23. 23. Faulty Heater <ul><li>Disconnect power. </li></ul>
  24. 24. Faulty Heater <ul><li>Trace your heater wire back to the terminals, you’ll find that they go back to your thermostat housing. </li></ul>
  25. 25. Faulty Heater <ul><li>Disconnect heater from thermostat. </li></ul>
  26. 26. Faulty Heater <ul><li>With your multi meter on the megger ohms scale, check the insulation resistance of the heater, if there is a reading on the megger, this shows that there is a short in the heater </li></ul>
  27. 27. Faulty Fan Motor <ul><li>The fourth fault we will cover is a service call to a domestic refrigerator; the customer is complaining his fridge is not cold. </li></ul>
  28. 28. Faulty Fan Motor <ul><li>The first thing you want to look at is the fan motor, note that some fan motors only run when the door switch is closed. </li></ul><ul><li>Locate the fan motor. </li></ul>
  29. 29. Faulty Fan Motor <ul><li>Disconnect power. </li></ul>
  30. 30. Faulty Fan Motor <ul><li>Find the fan motor wires and disconnect from the terminals. </li></ul>
  31. 31. Faulty Fan Motor <ul><li>Check the motor for resistance, the motor shows no resistance which means it is open circuited. </li></ul>
  32. 32. Conclusion <ul><li>Hopefully this presentation will help apprentices to quickly diagnose faults with domestic refrigerators/freezers. </li></ul>

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