E18
Thermador
Defrost Timer / Defrost Control Logic Fault
E18 displayed; unit may not defrost properly, leading to ice buildup and poor cooling.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Corrupted defrost algorithm in control board, Stuck defrost relay, Wiring issue in defrost control circuit, Main control board failure
How to Fix / Troubleshooting
Safety: Disconnect power before accessing the control board or evaporator area.
Steps:
- Check for ice buildup: Remove interior rear panel and inspect the evaporator. Heavy ice indicates defrost failure.
- Manual defrost: Turn off the unit and allow ice to melt naturally with towels in place. Do not use sharp tools or high heat.
- Verify heater and sensor: Test the defrost heater and defrost sensor as described for E4. If both are good, focus on the control board.
- Control board replacement: Remove the rear service panel, disconnect harnesses, and replace the main control board if the defrost relay is stuck or the board shows signs of failure.
After repair: Reassemble, restore power, and monitor for normal frost pattern and absence of E18.
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Repair Difficulty
Hard
4/5
Required Part
Main Control Board
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