Whirlpool TruCool™ Temperature Fluctuations: Fixing the... | appliancefaults.com

Technical Background:

The MCU (Microcontroller Unit) controls the defrost cycle based on inputs from temperature sensors (thermistors) and a timer. The defrost cycle activates the defrost heater, melting frost buildup on the evaporator coils. The melted water drains through the evaporator drain tube. Voltage paths include 120V AC to the defrost heater, controlled by a defrost relay on the main control board.

Symptoms:

The homeowner observes temperature fluctuations inside the refrigerator and freezer compartments. They may also notice ice buildup in the freezer, particularly around the evaporator coils. There might be water leaking from the bottom of the refrigerator.

Possible Causes:

Frozen evaporator drain.
Defective defrost heater.
Faulty defrost thermostat or timer.
Damaged door seals allowing warm air infiltration.
Malfunctioning thermistor.
Airflow obstruction inside the refrigerator.

Solution:

1

Unplug the refrigerator from the 120V AC outlet or turn off the breaker.
2

Locate the evaporator drain tube at the back of the freezer compartment.
3

Use a hair dryer or carefully pour warm water down the drain to melt any ice blockage. You can also use a turkey baster.
4

Check the defrost heater for continuity using a multimeter. A reading of approximately 20-40 ohms is expected. Replace if open.
5

Test the defrost thermostat for continuity when cold (below 40°F). It should show continuity. Replace if open.
6

Inspect door seals for damage or gaps. Replace if necessary.
7

Verify the thermistor resistance with a multimeter and compare it to the manufacturer's specifications for the current temperature. Replace if out of range.

Safety Warning:

Always disconnect power to the refrigerator before performing any repairs. Use proper Lock-Out/Tag-Out (LOTO) procedures to prevent accidental energizing of the circuit. Be aware of high voltage (120V AC) when testing electrical components.

Prevention:

Regularly clean the refrigerator's interior and door seals. Avoid overpacking the refrigerator, which can obstruct airflow. Periodically check the evaporator drain to ensure it's clear of debris. A yearly check of the door seals is advised.

Expert Tip:

To force a defrost cycle on some Whirlpool TruCool models, press and hold the freezer temperature DOWN and refrigerator temperature UP buttons simultaneously for 5 seconds. This enters service mode, allowing you to initiate a manual defrost cycle. Verify model-specific procedure.

Frequently Asked Questions

•What is the typical lifespan of a defrost heater?

The lifespan of a defrost heater can vary, but typically they last between 5-10 years. Factors like frequency of defrost cycles and voltage fluctuations can affect their longevity.

•How do I access the evaporator drain tube on my Whirlpool TruCool?

The evaporator drain tube is usually located at the back of the freezer compartment, often behind a panel covering the evaporator coils. You may need to remove a few screws to access it.

•What resistance value should I expect from the thermistor at 70°F?

The resistance value of the thermistor at 70°F will depend on the specific thermistor used in your Whirlpool TruCool model. Consult the service manual or component specifications for the correct value. A common range is between 5k to 10k ohms.

Whirlpool TruCool™ Temperature Fluctuations: Fixing the Evaporator Drain

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•What is the typical lifespan of a defrost heater?

•How do I access the evaporator drain tube on my Whirlpool TruCool?

•What resistance value should I expect from the thermistor at 70°F?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: