Microwave runs but does not heat; display shows E3 after a few seconds of operation.
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.
Possible Causes
How to Fix / Troubleshooting
Critical Safety Warning: The high-voltage section of a microwave (transformer, capacitor, diode, magnetron) can store and generate lethal voltages. Do not attempt internal high-voltage repairs unless you are qualified and know how to safely discharge the capacitor.
User-level checks:
- 1. Confirm symptom: Place a cup of water inside and run for 1–2 minutes. If the turntable, light, and fan operate but the water remains cold and E3 appears, the issue is in the high-voltage circuit.
- 2. Power reset: Unplug for 10 minutes, then retry. If E3 returns, internal components are likely faulty.
Technician-level checks:
- Unplug the microwave and remove the outer cabinet.
- Discharge the high-voltage capacitor using a proper resistor and insulated tools.
- Inspect the high-voltage transformer for burning, melted insulation, or a burnt smell.
- Test the high-voltage diode with a multimeter capable of diode testing; replace if shorted or open.
- Test the high-voltage capacitor for capacitance and leakage; replace if out of spec or shorted.
- Check any internal high-voltage fuse or thermal fuses in the HV circuit and replace only with identical rated parts.
Recommendation: Due to the danger and complexity, most users should have a professional service the high-voltage system on Tower microwaves.
Repair Difficulty
Required Part
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