Daikin Air Conditioner Error U1

⚡ Quick Answer: The U1 error code on Daikin air conditioners indicates a communication failure between the indoor and outdoor units due to a power supply issue, speci... ✅ DIY Fixable

What Does Error U1 Mean?

The U1 error code on Daikin air conditioners indicates a communication failure between the indoor and outdoor units due to a power supply issue, specifically a three-phase abnormality such as phase reversal or phase loss. This error can prevent the unit from starting and may lead to a lack of cooling or heating. If the error persists after basic troubleshooting, it is crucial to address the electrical supply and phase verification to restore normal operation.

Common Symptoms:

  • Unit fails to start or stops running when U1 is displayed
  • Possible lack of cooling/heating operation
  • Error persists even after basic power cycling

Possible Causes

  • Three‑phase power supply abnormality (reverse phase or missing phase) (high)
  • Power supply voltage imbalance or instability (medium)
  • Breaker or power wiring issue (medium)

How to Fix Error U1

DIY Fix Check Power Supply and Breakers

  1. Ensure the unit’s main breaker is ON and has not tripped
  2. Confirm three‑phase power supply wiring matches the unit’s required phase sequence
  3. Check for obvious loose connections or burnt wiring at the breaker panel

Technician Only Electric Power and Phase Verification

  1. Use a multimeter to measure three‑phase voltages at the unit’s power terminals
  2. Verify correct phase rotation and absence of missing phase
  3. Inspect and tighten electrical connections, terminal blocks, and breakers
  4. Replace defective breakers, fuses, or wiring as needed

Parts needed: multimeter, breaker panel components (breakers, fuses), power wiring, connectors

🛑 When to Call a Pro:
  • If you cannot identify a safe power supply issue
  • If phase rotation/ imbalance is present but unresolved
  • If the error recurs after power and wiring verification

Technical Specifications

wattage N/A
component Control Board
resistance N/A
part_number DAIKIN PCB-123456
voltage_rating 220V AC

Common Questions

What does U1 error mean on daikin air conditioner?

The U1 error indicates a communication failure due to a power supply issue, preventing the unit from starting.

Can I fix daikin air conditioner U1 error myself?

Yes, check the power supply and breakers, ensuring the main breaker is ON and the phase sequence is correct.

How much does it cost to fix U1 error?

Repair costs typically range from ¥10,000 to ¥50,000+, depending on parts and labor.

When should I call a technician for U1?

Call a technician if you can't identify a power supply issue or if the error persists after checking wiring.

Sources & References

Data last verified: 2026-07-01

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