Daikin Mini Split Error Code U3: How to Fix It

Q: What does Daikin error U3 mean?

Error U3 indicates that the transmission test between the indoor and outdoor units has not been executed or has failed. It usually points to wiring or communication issues.

Q: How do I clear error U3 on my Daikin mini split?

Try resetting the system by turning off power for 10 minutes. If that doesn't work, perform a manual transmission test using the TEST button on the outdoor PCB.

Q: Can I run my Daikin air conditioner with error U3?

No, the system typically will not operate correctly with this error. It may stop cooling/heating or run erratically until the communication issue is resolved.

Q: Is error U3 serious?

It's moderate. While it doesn't indicate an immediate safety hazard, it can prevent your unit from working and may lead to further issues if ignored.

Q: What tools do I need to fix error U3?

You'll need a multimeter to check voltage and continuity, and screwdrivers to access wiring panels and PCBs.

Abstract

Error code U3 on a Daikin mini split means the transmission test between the indoor and outdoor units hasn't been completed. This can prevent the system from operating correctly, often due to a wiring issue or a failed communication check.