Home AppliancesRefrigerator

How To Test Refrigerator Defrost Timer

Refrigerator 26

The refrigerator is an essential household appliance, and its smooth functioning is crucial for food preservation. One of the key components that ensure its efficiency is the defrost timer. This device regulates the defrost cycle in the refrigerator, preventing frost and ice buildup that could interfere with its operation. But, what happens if the defrost timer malfunctions? How do you test it? In this comprehensive guide, we will take you through a step-by-step process of testing a refrigerator defrost timer.


Testing a refrigerator defrost timer involves first disconnecting the power supply, then locating the defrost timer. Next, advance the timer by turning the advance screw until it clicks. Wait for about 35 minutes to check if it has left defrost mode and resumed cooling. If it doesn’t advance, the timer motor might be bad. Finally, use a multimeter set to the ohms setting X1 to check for continuity in the timer. If the timer fails these tests, it should be replaced.

Understanding the Defrost Timer

A refrigerator defrost timer is a device that regulates the defrosting cycle in the refrigerator. It works by periodically turning off the refrigerator’s compressor and evaporator fan motors, allowing the defrost system to melt any frost build-up. This process prevents the accumulation of frost in the refrigerator, which could lead to temperature fluctuations and reduced cooling efficiency.

Importance of Regular Testing

Regularly testing the defrost timer is crucial for maintaining the refrigerator’s optimal cooling efficiency, prolonging the equipment lifespan, ensuring food safety, preventing frost buildup, and avoiding potential damage. If the defrost timer malfunctions, it could lead to several issues such as temperature fluctuations, reduced cooling efficiency, and excessive frost buildup.

Signs of a Malfunctioning Defrost Timer

Identifying the signs of a malfunctioning defrost timer is the first step in testing it. Some common signs include:

  • The food in the freezer is soft, and cold drinks in the refrigerator are not as cold as they used to be.
  • Adjusting temperature settings does not result in colder temperatures.
  • Frost builds up on the freezer coils or the evaporator coil.
  • The refrigerator or freezer is too warm or stops cooling completely.

How to Test a Defrost Timer

Testing a defrost timer requires some tools and safety measures. You’ll need a multimeter to check for continuity in the defrost timer circuit, a screwdriver to remove the screws holding the defrost timer in place, and a refrigerator thermometer to check the temperature in the refrigerator.

Here’s a step-by-step guide:

  1. Disconnect the Power Supply: Ensure you disconnect the appliance’s power supply to avoid electrical shock.
  2. Locate the Defrost Timer: The defrost timer can be found behind the refrigerator’s lower kickplate, in the control panel, or behind the refrigerator near the compressor.
  3. Advance the Timer: Find the advance screw on the defrost timer and turn it clockwise until you hear it click. This advances the timer to the next mode. Wait about 35 minutes and check if it has left defrost mode and resumed cooling.
  4. Check for Timer Advancement: If the timer does not advance, the timer motor is probably bad, and the entire timer needs to be replaced.
  5. Test the Timer Electrically: Use a multitester set to the ohms setting X1 to test the timer for continuity. One pair of terminals should indicate continuity, and at least one pair should give a reading of infinity.

If the defrost timer fails these tests, it should be replaced. If you’re unsure about any of the steps or feel uncomfortable performing the test, consult with an appliance repair technician.


Testing a refrigerator’s defrost timer is a crucial maintenance task. It ensures that your refrigerator runs efficiently and prolongs its lifespan. By following the steps outlined above, you can easily diagnose and fix any issues with your defrost timer. However, if you’re unsure or uncomfortable performing these tasks, it’s always best to call in a professional.

Frequently Asked Questions

What is the function of a multimeter in testing the defrost timer?

A multimeter is used to test the timer for continuity. It measures the resistance in the circuit. If there’s no continuity, that means the electrical path is broken, indicating a faulty timer.

How often should the defrost timer be tested?

Ideally, you should test the defrost timer once a year or if you notice signs of malfunction such as excessive frost build-up or temperature fluctuations.

What does it mean when the defrost timer does not advance?

If the defrost timer does not advance, it means the timer motor is probably bad. In such a case, the entire timer needs to be replaced.

What safety measures should I take before testing the defrost timer?

Before testing the defrost timer, disconnect the power supply to the refrigerator to prevent any risk of electrical shock. Also, use the correct tools and follow the instructions carefully.

Can I replace a faulty defrost timer myself?

Yes, you can replace a faulty defrost timer yourself if you’re comfortable with the task. However, if you’re unsure about any steps or feel uncomfortable, it’s best to call in a professional appliance repair technician.

Leave a Comment

Your email address will not be published. Required fields are marked *