Fridge Spot Cooling, Appliance Home Repair Guide

Specific symptoms include: 1) Food not remaining at the desired temperature. 2) Fridge cools intermittently. 3) Food in freezer section thaws out and then refreezes or is only partially frozen.

When a fridge has intermittent cooling, it is known as “spot cooling.” Spot cooling is a situation where the fridge does not cool the food adequately for a period of time and then mysteriously returns to proper operating order. The erratic behavior in the fridge is caused by one of two things: a defective defrost timer, or a moisture restriction. First, check the defrost timer.

Check Defrost Timer

First, you must determine if the defrost timer is causing the fridge to heat and cool at the same time. It is not uncommon for a fridge to develop this problem. It simply means that while the fridge is running and cooling, the defrost timer is activating the defrost heater at the same time. This causes the food to thaw out in the freezer section and develop high fridge cabinet temperatures.

You can also use a volt/ohmmeter to check the defrost timer. Unplug the fridge power cord. Set the volt/ohmmeter on the RX-1 scale. Place one probe of the volt/ohmmeter on the timer terminal that supplies voltage to the defrost timer. Place the remaining probe of the volt/ohmmeter to the timer terminal that supplies voltage to the defrost heater (see your fridge wiring diagram). In most cases, you will use the #2 and #4 terminal of the defrost timer for this check. With probes connected use a knife or screwdriver to slowly turn tne defrost timer knob in a clockwise direction a complete revolution (360 degrees). While turning the screwdriver, look for any meter movement or deflection on the volt/ohmmeter scale. If there is any meter movement, repeat the check again. If meter movement is repeated, the defrost timer is defective internally. The defective defrost timer is the reason that the fridge is cooling intermittently in the cycle. To return the fridge to proper operating order, you will have to replace the faulty part.

Check For Moisture Restriction

Although a fridge system is supposedly a permanently sealed unit, it can be contaminated by water. This is called a “moisture restriction.” When moisture gets into the system it can cause intermittent cooling. There is no set pattern as to when this failure will occur. In some cases, fridges have been in service for seven to ten years and then have demonstrated this symptom.

How does moisture get into the sealed refrigeration system? At the manufacturer’s assembly plant, all refrigeration systems are charged with refrigerant in a contamination-free environment. In time, however, moisture has a way of entering the refrigeration sealed system no matter how careful the manufacturer is. This moisture mixes with the refrigeration oil and eventually finds it way to the bottom of the compressor case. The moisture in the oil may lie there undisturbed for days, weeks, and sometimes years before a problem develops. As the refrigeration oil is mixed with the refrigerant, the moisture works its way into the refrigerant lines on both the high side (condenser) and the low side (evaporator) of the refrigeration system.

The closed refrigeration system uses a device known as a dryer that is designed to trap water particles that enter the refrigeration sealed system. The dryer will absorb most of this moisture, but eventually it will become saturated. Water particles then find their way into the restrictor or capillary tube before entering the evaporator, the coldest point of the system. If the eariler check of the defrost timer as the possible cause of “spot cooling” proved negative, the problem is probably a moisture restriction.

To determine further if there is a moisture restriction, unplug the fridge power cord or turn the thermostat to the OFF position and leave it OFF for at least an hour with both the freezer and fridge doors open. If ice crystals have formed in the capillary tube and are restricting coolant flow, they will dissolve.

After an hour, plug the fridge power cord in and turn the thermostat to the ON position. Let the fridge run for about two hours. If the fridge begins to cool properly, you can be sure that there is a moisture restriction in the sealed system.

Do not assume that the fridge repaired itself if it starts to cool. Once the ice crystals have formed in the system, they will return in time. There is no way to predict when these ice crystals will reform in the fridge sealed system and again cause intermittent cooling problems.

REPAIR PROCEDURES

To Repair Moisture Restriction

If you have diagnosed a moisture restriction as the cause of the fridge “spot cooling,” call a qualified factory technician who is familiar with the sealed system of your fridge. Do not attempt this repair yourself, because it requires a thorough knowledge of a refrigeration sealed systems diagnosis and expensive special tools.

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