Need to install part #AP6978638, Heater

Refrigerator & Freezer Repair
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Brand:GE
Model Number:GTS18HGNGRWW
Main Symptom:Evaporator coils icing
What happens & when:Heavy ice on coils and heavy condensation in freezer continuously.

Error Code (if any):N/A
Parts or tests already tried:
Photos / video link:

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Yes if you are having heavy ice on your coils I’d check the heater element (GE WR55X31113 Refrigerator Defrost Heater And Harness Assembly | Genuine OEM Part) for continuity and if it fails I’d replace it.

The WR55X31113 on your GE GTS18HGNGRWW is the defrost heater and harness assembly. It includes the heater and wiring harness used during the automatic defrost cycle.

Tools Needed

  • Digital multimeter
  • 1/4" nut driver
  • Phillips screwdriver
  • Small flat-blade screwdriver
  • Needle-nose pliers
  • Work gloves
  • Hair dryer (optional for melting ice)

Live Power Warning

Extreme care should always be taken when testing live voltage. Contact with energized circuits can result in serious injury or death. If you’re not comfortable making live voltage measurements, disconnect power and perform resistance tests only.

If you’d like to learn more about using a multimeter, we’ve put together a comprehensive tutorial—check out the link in the description.

Accessing the Defrost Heater

  1. Unplug the refrigerator.
  2. Remove all food and shelves from the freezer.
  3. Remove the screws securing the rear freezer evaporator cover.
  4. Pull the cover forward and disconnect the evaporator fan connector if necessary.
  5. You’ll now see the evaporator coil with the WR55X31113 defrost heater mounted beneath it.

Test the Defrost Heater

Resistance Test (Power Off)

  1. Leave the refrigerator unplugged.
  2. Disconnect the heater harness.
  3. Set your multimeter to Ohms (Ω).
  4. Measure across the two heater terminals.

Expected Reading

  • Approximately 20–40 Ω (typically around 30 Ω).
  • OL (Open Loop) = Heater is failed.
  • Very low resistance (under 1 Ω) = Heater is shorted.

Check for 120 VAC During Defrost (Advanced)

Only perform this test if you’re comfortable working around live voltage.

  1. Reconnect the heater.
  2. Force the refrigerator into a defrost cycle (if applicable) or wait until it enters defrost.
  3. Back-probe the heater connector.

Expected Reading

  • 120 VAC present but the heater does not warm → Replace WR55X31113.
  • No 120 VAC → Continue diagnosing the main control board, wiring, or defrost sensor.

Replacing WR55X31113

  1. Unplug the refrigerator.
  2. Disconnect the heater harness.
  3. Release the retaining clips or brackets holding the heater to the evaporator.
  4. Remove the old heater assembly.
  5. Install the new heater in the same position beneath the evaporator.
  6. Secure the retaining clips.
  7. Route the harness exactly as the original to keep it away from the evaporator fan and moving parts.
  8. Reconnect the wiring harness.
  9. Reinstall the evaporator cover and shelves.
  10. Restore power.

After Replacement

The refrigerator should begin cooling immediately. It may take 24 hours for temperatures to stabilize. If the evaporator was heavily iced over, allow it to fully defrost before reassembling, or carefully melt the ice with a hair dryer, taking care not to overheat or damage plastic components.

If the New Heater Doesn’t Fix the Problem

If the heater tests good or replacing it doesn’t resolve the issue, the next items to test are:

  • Defrost thermistor
  • Main control board (for heater output during defrost)
  • Wiring harness connections between the board and heater

These components work together to control the automatic defrost system.