Maytag Refrigerator Evaporator Coils Frozen:... | appliancefaults.com

Technical Background:

The refrigerator's Main Control Unit (MCU) manages the defrost cycle. The MCU relies on input from the defrost timer (or integrated timer in the MCU), the defrost thermostat, and temperature sensors to determine when to initiate the defrost cycle. The defrost heater melts the ice buildup. A failure in any of these components, or related wiring, can disrupt the cycle, leading to excessive ice accumulation.

Symptoms:

The homeowner reports that the evaporator coils in their Maytag refrigerator are completely frozen over, restricting airflow and reducing cooling efficiency. However, the defrost heater has been tested and is confirmed to be functioning correctly.

Possible Causes:

Defrost timer malfunction: Stuck in cooling mode.
Defrost thermostat: Fails to register temperature change or remains open.
Faulty wiring: Open circuit in defrost circuit.
Main Control Board (MCU) failure: Not initiating defrost cycle.
Airflow restriction: Blockage preventing proper air circulation across the coils.
Damaged defrost termination thermostat.

Solution:

1

Unplug the refrigerator or turn off the breaker at the breaker panel.
2

Locate the defrost timer. On older models, manually advance the timer into the defrost cycle. Listen for the compressor to shut off and the defrost heater to activate. If it doesn't, the timer is likely faulty.
3

Locate the defrost thermostat on the evaporator coil. Use a multimeter to test for continuity. It should be closed when cold (around 32 degrees Fahrenheit). If open, replace it.
4

Check the wiring harness connecting the defrost heater, thermostat, and control board for any breaks or loose connections.
5

Access the Main Control Board (MCU). Use a multimeter to check the voltage output to the defrost heater during the defrost cycle (should be 120V AC). If there's no voltage, the board may be faulty.
6

Inspect the evaporator fan motor. Ensure it's running properly to circulate air.
7

If the defrost system is controlled electronically, run the service diagnostic test and check for error codes relating to the defrost system. Refer to the service manual.

Safety Warning:

Always disconnect power to the refrigerator before performing any repairs. Use proper Lock Out/Tag Out (LOTO) procedures. High voltage is present in the control circuits.

Prevention:

• Regularly clean the condenser coils (located at the back or bottom of the refrigerator) every 6 months to improve efficiency.
• Ensure proper door seals to prevent warm air from entering the refrigerator, which can increase frost buildup.
• Avoid overpacking the refrigerator, which can restrict airflow.

Expert Tip:

On some Maytag models, you can force a defrost cycle through the service mode. To enter service mode, simultaneously press and hold the freezer temperature DOWN and refrigerator temperature UP buttons for approximately 5 seconds. Refer to the service manual for specific instructions and codes for initiating a defrost cycle.

Frequently Asked Questions

•How do I test the defrost timer if I can't manually advance it?

You can test the defrost timer by disconnecting it and using a multimeter to check for continuity across the terminals. Refer to the wiring diagram to identify the correct terminals. If there's no continuity when the timer should be in a cooling cycle, the timer is faulty.

•Where is the defrost thermostat located on my Maytag refrigerator?

The defrost thermostat is typically located on the evaporator coil assembly, often clipped directly to one of the coils. It's usually a small, round or rectangular component with two wires attached.

•How often should the defrost cycle occur on a Maytag refrigerator?

Most Maytag refrigerators are designed to run a defrost cycle approximately every 8 to 12 hours of compressor run time. The exact frequency may vary depending on the model and usage patterns.

Maytag Refrigerator Evaporator Coils Frozen: Troubleshooting Guide

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip:

Frequently Asked Questions

•How do I test the defrost timer if I can't manually advance it?

•Where is the defrost thermostat located on my Maytag refrigerator?

•How often should the defrost cycle occur on a Maytag refrigerator?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Expert Tip: