Fridge Testing Fault finding and Basic Repairs

Tired of inexperienced repairmen , i did some investigating , here is what i can share:-

When you switch the fridge off always give it at least 15 minutes rest before you turn it on again.

Problem : U left the door open for a while: Now it is not cooling properly.

Humidity has turned to ice and has blocked the cooling system.

Solution Let ur fridge thaw …ie switch it Off and keep the doors open for a day or two and then switch it On again . Be prepared to remove excess water from the back of the fridge ie in the tray above or besides the compressor or the black oval thinge.

Check out

Problem : Freezer Frozen Solid , Noisy obstructed fan, Frost free fridge not defrosting

1. Fan : Check if it is working or not. If  blocked check 2 and 3.

2. Bimetallic Thermostat: Good if continuity is YES when cold and NO when room temperature  : Bad otherwise or  if puffy or if not good

3. Heating Coil or heater : Bad if Continuity is broken or if MM reads 1
: Good if Continuity is ok or if MultiMeter reads 0.

Generally a bad  thermal fuse with no Continuity could be a sign of bad heating coil, or bad circuit or defrost timer.

If both are ok Problem is more serious and could be the Circuit, Timer or Temperature sensors.

Disconnect 2 and 3 from circuit for 6 to 8 hrs and chk out cooling and frost buildup to isolate whether problem is in 4 or 5.

4. Temperature sensor / Thermistor: 

Generally there are thermistors in both sections freezer and fridge.

  • Fridge /Freezer section too warm or too cold
  • Refrigerator runs too long or short.

Faultfinding : Resistance in a thermistor  increases as temp drops and vice versa. At room temperature 68°F.,the sensor should read approximately 6.1K Ohms. With the thermistor submerged is a glass full of ice water, the sensor should be very close to 32°F which should read approximately 16.3K Ohms

5. Circuit or Mechanical Defrost timer

The circuit board is damaged or the mechanical timer is  stuck .

For mech defrost timers  watch :-

How the Fridge cooling System works 

Liquid refrigerant (Freon/ R134a) entering the evaporator begins to boil into a gas because of the sudden drop in pressure created by the compressor. This change of state absorbs heat. The temperature inside the evaporator coil may be -20 degrees F. This will condense and freeze moisture in the air in contact with the coil (which is why we have to defrost). If there is freon boiling inside the evaporator this frosting will occur within minutes. So if we run the unit with the cover off the evaporator and no frost forms we can know that there really is no freon or the the system is clogged. If the unit runs for several minutes with the door closed and the freon charge is correct, the frosting should form all along the length of the evaporator.

If the cooling system is good in a top freezer fridge , when the compressor has run for some time and is still running :-

  1. The compressor and the  line connecting to it should be very hot.
  2. Touch the radiation coil,  should be cooler on one side and hotter on the other or hotter at the top getting cooler as it goes down.
  3. You can feel the filter dryer and the thin capillary tube connected to it  and you will feel liquid is passing through it …
  4. The fridge should sound like a blizzard if you put your ear to it.
  5. Switch it off and you should get gurgling sound as the fridge balances itself out.

Major Problem : Fridge doesn’t cool properly

1. Could be a choke or a leak  in the cooling system,

2. Could be a  clogged filter dryer or  capillary tube, or worse in the radiator or co

3. Could be a gas leak  or low on gas because of age or leakage ..

The fridge has to be regfilled with R134a

Major Problem : Fridge does not start !

Check the relay

Check  the  compressor

Check the Cooling system, for problem with the defrost Circuit board or mechanical defrost timer.

Service and parts guy in Mumbai,

Lamington Road

Devi Sales at Dadar  in Mumbai keep parts and service all fridges and A/Cs.

Supra Service Helpline No: 9821516165, 9167761722, 28670125

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If ur a techie try reading The Fridgeman Blog .


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