Solving Fridge-Freezer Cooling Issues: A Complete Diagnostic Guide

Gemini said

SAFETY DISCLAIMER: Improper cooling can lead to foodborne illness. Always ensure your refrigerator maintains a temperature below 40°F (4°C). Disconnect power before inspecting internal fans or electrical components.

When a refrigerator stops cooling, it doesn’t always mean the compressor is dead. Often, the issue is a simple airflow blockage or a faulty sensor that can be fixed with basic tools.

Key Diagnostic Tips:

• Airflow Blockage: If the freezer is freezing but the fridge is warm, check the "damper" door. If it’s stuck closed, cold air can’t reach the fresh food section.

• Frost Buildup: Heavy frost on the back wall of the freezer indicates a defrost failure. This "ice dam" blocks the evaporator fan from circulating cold air.

• Dirty Condenser Coils: If the coils under or behind the unit are layered in dust, the fridge cannot shed heat, causing the internal temperature to rise steadily.

Improved Repair Strategy:

1. The Manual Defrost: If you see heavy ice, unplug the unit for 24 hours with the doors open. This clears the airway and may temporarily restore cooling while you order parts.

2. Test the Evaporator Fan: Open the freezer door and manually press the door switch. If you don’t hear the fan start spinning, the motor may be burnt out.

3. Check the Thermistor: Use a multimeter to test the resistance of the temperature sensors. They should change resistance as they get colder; if the reading stays "Open," replace the sensor.

4. Seal Inspection: Clean the door gaskets with warm soapy water. A small gap in the seal lets in warm, moist air, causing the cooling system to overwork and fail.

In order for the cooling process to occur we need to evaporate a liquid into a gas which causes the cooling, we then need to condense that gas back into a liquid in order to start the process once again.

The gas we use today is R600a but in the past R12 ( banned ) and R134a ( phasing out ).

The system is vacuumed out before the gas is put into the system, when the system is filled to the correct amount of gas the system is ready to be turned on, the compressor which is the engine of the system has a low pressor and high pressure side it collects vapour from the low side from the evaporator and forces vapour into the high side towards the condenser. The compressor creates a high pressure in the vapour as it forces it toward the condenser due to this the vapour will become hot or super-heated as it is known if this process. The condenser being designed similar to a radiator will begin to radiate this heat out it the condenser is usually fitted with a fan to speed the heat loss up, by the time the vapour/refrigerant has gone through the condenser it will have cooled enough to return to a liquid this will now be a warm high pressure liquid.

This liquid then passes through the drier filer ( click for more details ) and through a very small bore pipe called the capillary on its way to the evaporator, when the liquid hits the evaporator the pressure drops immediately which causes the liquid the vaporize and and change from liquid to vapour this will cause the evaporator to drop in temperature this will start to remove the heat from the air surrounding the evaporator causing the temperature in the fridge freezer to drop.

The vapour then returns to the compressor and the process begins all over again.