U4 🟡 Repair Required

Daikin Error Code U4: Communication Error Indoor/Outdoor

⚠️ Your Daikin HVAC system has a communication error between the indoor and outdoor units. It's safe to use, but you should schedule a professional repair soon.

How to Fix Daikin Code U4

  1. Check for any visible damage to the communication wire connecting your indoor and outdoor units. If you find any damage, do not attempt to repair it yourself.
  2. If the wire appears undamaged, the issue may be with the control board or refrigerant pressure sensor. These components require professional diagnosis and repair.
Type: digital display Display: remote controller

What Does Daikin Error Code U4 Mean?

The Daikin U4 error code indicates a communication issue between your indoor and outdoor HVAC units. This could be due to a faulty communication wire, a problem with the control board, or an issue with the refrigerant pressure sensor. The system will continue to operate, but you may notice reduced performance or comfort.

Common Causes of Daikin Code U4

  • Faulty communication wire between indoor and outdoor units
  • Problem with the control board in either the indoor or outdoor unit
  • Issue with the refrigerant pressure sensor in the outdoor unit

Applicable Daikin Models

Daikin Comfort⚡Daikin Fit⚡Daikin Intelligent Touch⚡Daikin Latitude⚡Daikin Unitary System⚡FIT⚡Inverter Ducted Split System⚡LV Series⚡MXS⚡Multi-Zone⚡NCB⚡NCM⚡NCV⚡NCW⚡NMB⚡NMP⚡NPE⚡NTV⚡NW🔥NWZ⚡Quaternity⚡SkyAir⚡VRV⚡VRV IV⚡
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Replacement Parts for Daikin Mini-Split Code U4

Communication Wire
Control Board OEM: 44518C1601
Refrigerant Pressure Sensor OEM: 44518C1602