Daikin Air Conditioner Error U4-00
⚡ Quick Answer: The Daikin air conditioner U4-00 error indicates a communication failure between the indoor and outdoor units. This issue often results in the AC unit... ✅ DIY Fixable
What Does Error U4-00 Mean?
The Daikin air conditioner U4-00 error indicates a communication failure between the indoor and outdoor units. This issue often results in the AC unit not operating, with symptoms such as a blinking display and intermittent functionality. When this error occurs, it is crucial to address the communication fault to restore normal operation.
Common Symptoms:
- Indoor and outdoor units fail to communicate and unit stops running
- Air conditioner does not start or stops operation with U4 displayed
- Blinking error lights or communication error indication
Possible Causes
- Communication fault between indoor and outdoor units (medium)
How to Fix Error U4-00
DIY Fix Power reset and basic inspection
- Turn off the AC unit from the breaker
- Wait 5–10 minutes
- Turn the breaker back on and restart the unit
- Check if the U4 error persists
Technician Only Inspect communication wiring and control boards
- Check the communication wiring between indoor and outdoor units for continuity and proper connections
- Inspect indoor and outdoor PCBs for damage or faults
- Replace any defective wiring or control boards as needed
- Verify proper addressing and termination of communication lines
Parts needed: Communication wiring/connectors, Indoor unit PCB, Outdoor unit PCB
- If error persists after power reset
- If there are signs of PCB damage, burning smell, or frequent tripping
- If wiring faults are suspected but cannot be safely accessed
Technical Specifications
| wattage | N/A |
|---|---|
| component | Control Board |
| resistance | N/A |
| part_number | DAIKIN 4E-1000 |
| voltage_rating | 220V AC |
Common Questions
What does U4-00 error mean on daikin air conditioner?
The U4-00 error indicates a communication failure between the indoor and outdoor units, causing the unit to stop running.
Can I fix daikin air conditioner U4-00 error myself?
Yes, you can perform a power reset by turning off the unit at the breaker, waiting 5-10 minutes, and then restarting.
How much does it cost to fix U4-00 error?
Repair costs for the U4-00 error typically range from ¥20,000 to ¥80,000, depending on parts and labor.
When should I call a technician for U4-00?
Call a technician if the error persists after a power reset, if you notice PCB damage, or if there are suspected wiring faults.
Sources & References
- Daikin Error Code Search (official)
- Daikin Error Code U4: Meaning, Causes, and Solutions (community)
Data last verified: 2026-07-07
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