Tristar
Door Interlock System Failure (Serious Safety Hazard)
Microwave runs with the door open or starts when the door is closed without pressing START.
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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
Shorted or welded door switch contacts, Miswired interlock switches, Broken interlock mounting bracket, Control board relay stuck closed
How to Fix / Troubleshooting
Immediate safety warning: Unplug the microwave immediately and do not use it. A microwave that runs with the door open is extremely dangerous.
Steps (for technicians or experienced DIYers only):
- 1. Verify symptom: Confirm that the turntable or fan runs with the door open or without pressing START. Do not continue testing.
- 2. Inspect interlock switches: With the cabinet removed, check all door switches for signs of melting or welded contacts. Replace the entire interlock switch set if any switch is suspect.
- 3. Check wiring: Ensure the switches are wired according to the Tristar wiring diagram. Correct any miswiring.
- 4. Control board check: If switches and wiring are correct but the unit still runs unexpectedly, the control board relay may be stuck and the board must be replaced.
- 5. Professional verification: Have a qualified technician verify safe operation before returning the microwave to service.
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Repair Difficulty
Professional Required
5/5
Required Part
Door Interlock Switch Kit
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