How To Fix A Refrigerator That's Running Too Long

The defrost timer can be either a mechanical timer or an electronic “adaptive defrost control”. Both are used to initiate the defrost cycle by turning on the defrost heater at specific intervals and for a specific amount of time. Mechanical timers are more common and usually activate a defrost cycle every 8-10 hours of compressor run time. This normally occurs about once every day or two. The defrost cycle will normally terminate after 20 to 30 minutes and the compressor and fans will start again. Adaptive defrost controls will monitor ambient conditions and previous defrost cycles and adapt the defrost cycle frequency and length to be more efficient.

Mechanical timers can be checked with a multi-meter for continuity and most can also be manually advanced with a flat blade screwdriver. The slot for the advance gear is normally located in the center of the timer and can only be turned in one direction. You will normally hear a loud click when the internal cam engages the heater switch. If the timer does not advance on its own, or if the internal switch does not engage, then the timer will need to be replaced. The defrost timer can usually be found near the bottom of the refrigerator behind the kick plate, in the control panel or in the back of some side-by-side units.

The Defrost Heater is located below and next to the evaporator coils and is controlled by the defrost timer or adaptive defrost control and the defrost termination thermostat. The heater is normally a glass encased heater wire with well insulated wire leads. The heater coil can be checked for continuity with a multi-meter. Power must be removed before performing this test.

The defrost termination thermostat is located on the evaporator coils and is used as a safety device to turn off the defrost heater when the temperature reaches a specific limit. The thermostat is normally wired in series with the defrost element and is normally open circuit above 35°- 47° degrees Fahrenheit. For this reason it is sometimes difficult to check the continuity of the thermostat unless you are sure that the temperature is low enough to close the circuit. Newer style thermostats may have an internal bias resistor to aid in testing both the thermostat and the heater. The wiring diagram will normally indicate this. A continuity check of the heater circuit would show a low resistance if the heater is good and the thermostat closed, a higher resistance if the heater is good and the thermostat open and no continuity if the heater is open. Power will have to be removed to perform these tests.

Leaky or damaged door seals can create long run times but normally will just create excess moisture that is visible near the air outlet ducts or on shelves in the freezer. Moisture along the edge of the door is also a good indication that the gaskets are not sealing properly and should be replaced.

If your fridge sounds like it’s running more often than normal, the condenser fan motor could be to blame. If the condenser cannot expel heat efficiently, then the compressor and sealed system work harder to keep the refrigerator cold. Check for higher than normal surface temperatures on the cabinet between the fresh food and freezer doors as this area contains tubing attached to the condenser and will heat up if the condenser cannot be cooled fast enough.

The condenser and motor are located at the rear of the refrigerator next to the compressor, and can be accessed by removing the back panel. Verify that the condenser fan motor operates when the compressor is on and check for any restrictions in the airflow that might contribute to this symptom. If the fan does not come on with the compressor, then check to see if the motor or fan may be seized and replace if defective. Verify that power is supplied to the fan motor terminals and that the connections are tight. The motor can be checked for continuity and voltage with a multi-meter. Live voltage checks should only be performed by qualified persons.

The evaporator fan is used to draw air over the evaporator coil and circulate the cold air throughout the fresh food and freezer compartments. If the evaporator fan does not work then the control thermostat or sensor may not correctly sense the temperature and the compressor will continue to run longer than normal. The fresh food and freezer compartment temperatures will increase as well.

The evaporator motor and fan are located in the freezer compartment and you can normally here the motor or feel the air movement when running. If you suspect that the fan motor is not running properly, then turn off the refrigerator and remove the evaporator fan cover. Verify that the fan blade is secure and that the motor is not seized. You can check the motor for continuity with a multi-meter. You can also verify that power is applied to the motor when the compressor is running. This is a live voltage check and should only be performed by a qualified person.

The sealed system in a refrigerator is comprised of the evaporator, the condenser and the compressor and the associated tubing. A defect in any of these components can cause a symptom of running too long or not cooling enough, and would have to be serviced by a qualified refrigeration technician.