HVAC Code Lookup

Daikin Mini-Split Code UA

Soft lockout

On pair systems, unspecified voltage between indoor and outdoor unit - a pair-type and a multi-type unit have been connected together. On multi-zone systems the same code means mismatching of indoor and outdoor units or too many indoor units connected.

Manual wording: “UA Unspecified voltage (between indoor unit and outdoor unit)”

Documented for: All Daikin residential ductless; meaning differs between pair and multi-zone platforms

Likely causes, most common first

  1. Wrong models interconnected
  2. Wrong wiring of connecting wires
  3. Wrong indoor unit PCB or outdoor unit PCB mounted
  4. Defective indoor unit PCB
  5. Defective outdoor unit PCB
  6. Excess of connected indoor units (multi-zone)
  7. Mismatching of the refrigerant type of indoor and outdoor unit (multi-zone)
  8. Outdoor unit PCB setting not performed after replacing with a spare parts PCB (multi-zone)

What you can safely check yourself

  • Turn the system off at the breaker or disconnect switch, wait a minute, and turn it back on once

When to call a technician

UA is essentially an installation or parts-compatibility problem. Whoever installed or last serviced the system needs to verify the indoor/outdoor combination and the wiring.

A Daikin mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Daikin codes