Daikin Air Conditioner Error Code UH

The UH code means the system encountered a refrigerant system address abnormality because the auto-addressing process did not successfully assign a system address to one or more indoor units. This communication process is required for the system to coordinate operation across all connected units. It most commonly appears after a new installation, a PCB replacement, or a transmission wiring fault.

A power reset may allow the auto-addressing sequence to restart and complete successfully, particularly if the error was triggered by a momentary power interruption during the initial startup process. However, if an underlying cause such as a wiring fault or failed PCB is present, the UH code will return after reset. Resetting without addressing the root cause is not a permanent fix.

If the fix is simply allowing the auto-addressing sequence to complete or correcting a loose wiring connection, costs are minimal and may only involve a service call fee, typically in the range of $75 to $200. If a faulty indoor or outdoor unit PCB needs replacement, parts and labor can range from $300 to $900 or more depending on the unit model and the specific board required. Getting a diagnostic visit from a certified Daikin technician is the most reliable way to determine the actual repair cost.

If UH appears immediately after a new installation, you may simply need to wait for the auto-addressing sequence to complete on first power-on. However, if the error persists, diagnosing transmission wiring faults and PCB issues requires familiarity with low-voltage communication circuits and multi-zone system architecture. Most persistent UH faults should be handled by a qualified HVAC technician to avoid wiring errors that could damage system components.

A UH fault means the system has not completed its required addressing and configuration sequence, so normal operation is not available while the error is active. Attempting to force operation in this state is not recommended, as the system cannot properly manage refrigerant flow across unaddressed units. The system should be left in a safe standby state until the fault is resolved.