How to Test a Refrigerator Defrost Heater With a Multimeter

The person typing how to test a refrigerator defrost heater with a multimeter wants to know whether the heater that melts frost off the freezer evaporator has failed, and how to confirm it with a meter. The short answer: unplug the refrigerator, disconnect the heater, measure its resistance in ohms, and compare the reading with the value listed for your exact model. An open reading (OL) points to a failed heater. The sources we opened do not give a resistance figure for a defrost heater, so the target value has to come from your model’s service data.

Quick answer

• Unplug the refrigerator from the wall socket before you touch any wiring. Electrolux’s service guidance says to deactivate the appliance and disconnect the mains plug before any repair or maintenance.
• Put the meter in resistance (Ω) mode, disconnect the heater from its wiring, and read across the heater’s two terminals.
• An OL or open reading means the heater circuit is broken. A reading that does not match your model’s specification also means the heater should be checked further or replaced.
• The opened sources do not state a resistance value for defrost heaters, so the number must come from the service sheet or parts data for your model.

What the defrost heater does

A defrost heater sits in the evaporator section at the back of the freezer compartment. GE’s description of its defrost system says the heater melts frost off the evaporator coils and then turns off. When the heater is working, it is normal to see a red, yellow or orange glow from the freezer. GE also says that water dripping or sizzling as it hits the heater is normal, because the heater helps evaporate the melted frost before it reaches the drip pan.

This matters for testing. Frost on the evaporator can have causes other than a failed heater, including the defrost control, the thermostat or the timer. A resistance test only tells you about the heater itself, so it is one step in a larger check.

GE also notes that defrost cycles differ by model. Its page says that on Adaptive Defrost models, a defrost usually lasts approximately 25 to 45 minutes and happens once or twice a day. Timer-based models defrost every 8 to 15 hours, depending on the model, and some models have a thermostat on the evaporator coils that starts a defrost. GE also says that manual models have no defrost heater at all. Check the model type before you start, because a manual-defrost unit will not have a heater to test.

Tools you need

• A digital multimeter with a resistance (Ω) setting. Fluke’s guidance describes the ohms function as the way to measure component resistance.
• A way to see the heater’s wire terminals, such as a flashlight.
• The model number of the refrigerator, so you can find the matching service data or part specification.
• A non-contact voltage tester, if you want an extra check that the heater is not powered before you touch its terminals. Use it as a check only; the unplugging step is the main safety step.

Step by step: test the heater with the meter

Step 1: Unplug the refrigerator

Pull the plug from the wall socket. Electrolux’s guidance is to deactivate the appliance and disconnect the mains plug from the socket before any repair or maintenance operation. If the appliance is hard-wired with no plug, shut off the breaker that supplies it and confirm it is off before you work. The sources we opened do not cover hard-wired connections, so follow the manufacturer’s instructions for your model.

Step 2: Let the appliance cool and locate the heater

Electrolux also says to make sure the appliance is not hot before any repair. Then locate the heater in the evaporator section at the back of the freezer, as GE describes. Remove any cover carefully, and take a photo of the wiring before you disconnect anything. A photo is the easiest way to remember how the wires went back together.

Step 3: Discharge any capacitors in the circuit

Fluke’s guidance says that if a circuit includes a capacitor, you should discharge the capacitor before taking any resistance reading. The sources we opened do not say which refrigerator circuits contain capacitors, so check the wiring for your model before assuming the heater circuit is free of stored energy. If you are not sure how to discharge a capacitor, stop here and call a qualified appliance technician.

Step 4: Isolate the heater from the wiring

Fluke says the best results come when the component being tested is removed from the circuit, and that other parts in parallel can skew the reading. Disconnect at least one heater lead from the harness so the meter reads only the heater. Pull the connector straight out rather than prying on the wires.

Step 5: Set the meter and check its own leads

Plug the black lead into COM and the red lead into the VΩ jack. Turn the dial to the ohms position. Fluke says the display should show OLΩ before you connect anything to the component. If the display does not show OL with the leads apart, check the leads and the meter battery before you trust a reading. Fluke also advises to avoid touching the metal parts of the test leads during a measurement, because your body can act as a parallel path and lower the reading.

Step 6: Read the heater

Touch one probe to each heater terminal and hold the probes steady. Read the value on the display, and note the reading and the units. Fluke’s guide notes that the meter can autorange, or you can set the range manually. Write the reading down before you move the probes.

Step 7: Interpret the result

• OL (open): the heater circuit is open. This is the most common sign of a failed heater, and the heater should be replaced. Check that the connector and wires are not broken before you order a part, because a broken wire can look the same on the meter.
• A reading close to zero: this can mean the heater is shorted or that the leads are touching each other. Separate the leads, reset the meter, and test again. Before you rely on a low reading, check the leads by touching them together and confirming the meter’s display.
• A reading inside the specified range: the heater element is likely intact. If the freezer still frosts, the defrost thermostat, timer or control, and the wiring to the heater are also worth checking before you replace the heater.
• A reading outside the specified range but not OL: the heater may be aging or out of tolerance. Compare with the service data for your model before you decide.

Where to find the correct resistance value

The opened sources do not give a single ohm value for every refrigerator. Defrost heater resistance depends on the heater’s design, its wattage and the model. Use these places to find the target value:

• The service data sheet for your exact model number, from the manufacturer’s support site.
• The part label or the part description for the replacement heater, which may list its voltage and wattage.
• The manufacturer’s support line, which can confirm the correct test value for your model.

Do not use a value from a different model or from an unverified forum post. A heater with the wrong resistance can run too hot, fail early, or fail to melt frost properly.

Safety notes

Electrical work on a refrigerator can expose you to line voltage if the appliance is not fully isolated, so unplug it and keep the meter leads away from moving fan blades. Keep water away from the wiring and the connector. If the evaporator section cannot be opened safely, or if the wiring looks burned or melted, stop and call a qualified appliance technician.

How we chose the method

This guide uses the method from the sources we opened: GE’s description of the defrost system, Fluke’s resistance measurement steps and Electrolux’s guidance on deactivating an appliance before service. We did not choose the method from product listings. We did not look at prices or ratings for any meter. The steps are written to match what those sources state.

What we could not verify

• The sources we opened do not give a resistance value for defrost heaters. The reading you should expect depends on your model, and the value must come from the service data for that model.
• We did not confirm the wiring diagram for any specific refrigerator model. The layout of the connector and the thermostat varies by model.
• We did not verify which refrigerator models use which defrost control. Check the service sheet for your model.

Common mistakes to avoid

• Testing the heater while the refrigerator is still plugged in. Unplug it first, as Electrolux’s guidance says.
• Reading a heater while it is still wired into the harness. Fluke says other components in parallel can skew the reading, so disconnect at least one lead.
• Assuming a normal reading means the heater is fine when the freezer still frosts. The thermostat, the timer or the control may be the fault.
• Using a resistance value from another model. Fluke and GE both point to checking the value for the specific model.

FAQ

Can I test a defrost heater with the refrigerator plugged in?

No. Electrolux’s guidance is to deactivate the appliance and disconnect the mains plug before any repair or maintenance. Test with the power off.

What does OL mean on the meter?

Fluke describes OL on its meters as a reading where the resistance is greater than the meter can measure. On a defrost heater, OL suggests the heater circuit is broken.

Is a red glow from the heater normal?

GE says it is normal to see a red, yellow or orange glow from the freezer when the defrost heater is on.

Does every refrigerator have a defrost heater?

No. GE says manual models have no defrost heater. Check your model type first.

Why does my freezer still frost after the heater tests fine?

The defrost thermostat, the timer or control, a door seal problem or a fan problem can also cause frost. The heater test covers only the heater.

Should I replace the heater myself?

Replacing a heater means matching the part to your model. For wiring faults, burned connectors or sealed evaporator sections, call a qualified technician.

Bottom line

Unplug the refrigerator, disconnect one heater lead, read the heater’s resistance, and compare that reading with the service value for your exact model. An open reading means the heater should be replaced. Anything else means check the thermostat, timer and wiring before you spend money on a part.

See also our guides: the auto-ranging digital multimeter guide for choosing a meter with automatic range selection, and how to check a fuse with a multimeter for another low-voltage resistance check.

Sources

• GE Appliances, “Refrigerator and Freezer – Types of Defrost Systems”, opened 2026-10-27: https://products.geappliances.com/appliance/gea-support-search-content?contentId=19471
• Fluke, “How to Measure Resistance with a Digital Multimeter”, opened 2026-10-27: https://www.fluke.com/en-us/learn/blog/digital-multimeters/how-to-measure-resistance
• Fluke, “How to Use a Multimeter: A Comprehensive Guide”, opened 2026-10-27: https://www.fluke.com/en-us/learn/blog/maintenance-monitoring/how-to-use-a-multimeter-guide
• Electrolux Group support, “How to replace upper heating element (1)”, opened 2026-10-27: https://support.electrolux.co.uk/support-articles/article/how-to-replace-upper-heating-element-1

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