Mitsubishi Error Code 7100: Inverter / IPM Contact Fault

Quick Answer — Mitsubishi Error Code 7100

Error code 7100 on Mitsubishi CITY MULTI systems indicates a fault in the inverter’s IPM (Intelligent Power Module) or its contact circuit.

The system halts compressor operation after detecting internal current leakage, IGBT failure, or IPM overheating.

Most frequent causes: faulty IPM module (40 %), shorted IGBT transistor (30 %), or inverter cooling failure (20 %).

Power off the unit immediately and allow it to cool before testing with a multimeter.

Average repair cost: $600 – $1 200; full inverter board replacement $1 800 – $2 200.

Fixair inverter specialists resolve over 85 % of 7100 faults within 24 hours.

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What 7100 Means

Error 7100 is triggered when the inverter’s self-diagnostic circuit detects improper current or voltage flow through the power module.

This usually occurs during compressor startup or load transition.

The IPM acts as the “brain and muscle” of the inverter, and any anomaly can cause the system to stop to prevent catastrophic component damage.

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Main Causes of 7100

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1. Defective IPM Module (≈ 40 %) — Internal semiconductor failure causes current imbalance.
2. Shorted IGBT Transistor (≈ 30 %) — Excessive switching current leads to short circuit.
3. Inverter Cooling Failure (≈ 20 %) — Fan or thermal grease degradation overheats components.
4. Wiring or Connector Damage (≈ 10 %) — Poor contact between PCB and IPM socket.

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Immediate Safety Steps

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1. Power off the system completely.
2. Wait 10 minutes for inverter capacitors to discharge.
3. Inspect for burnt smell, discoloration, or damaged components on the PCB.
4. Do not restart until a professional tests the inverter module with proper equipment.
5. Schedule a Fixair inverter diagnostic to confirm whether the IPM or IGBT needs replacement.

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Repair Costs and Timeframes (2025)

Minor connection or cooling issues: $600 – $900 (2–3 hours).

IPM replacement: $900 – $1 200 (3–4 hours).

Full inverter board replacement: $1 800 – $2 200 (5–6 hours, including calibration).

Fixair technicians provide full load and thermal testing after repairs to confirm inverter safety.

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Prevention Tips

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• Maintain proper ventilation around the outdoor inverter enclosure.
• Clean inverter fans and check for obstructions quarterly.
• Schedule annual board inspections to test IPM thermistors and capacitors.
• Use surge protection and stable grounding to prevent transistor damage.
• Routine inverter maintenance reduces 7100 recurrence by over 80 %.

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Frequently Asked Questions

Is 7100 dangerous?

Yes. It signals internal inverter faults that can lead to power failure or fire if left energized.

Can I reset it myself?

No. Resetting without electrical testing risks further damage. Always have an HVAC professional test the IPM.

How much does it cost to fix?

$600 – $1 200 for IPM or IGBT repair; $1 800 – $2 200 for complete inverter replacement.

How long does it take?

2–4 hours for minor repairs, up to 6 hours for full board replacement.

Will it come back?

Not if the new IPM is properly installed and thermal management is maintained.

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Summary

Error code 7100 indicates an inverter or IPM contact fault in Mitsubishi CITY MULTI outdoor units.

It’s a critical safety stop protecting the compressor and power electronics.

Turn off the system and schedule professional inverter service immediately.

Most repairs are completed within a day for under $1 200.

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