Error code reference

Daikin Air Conditioner Error Code U4

Transmission error between indoor units and outdoor units - transmission not normal for extended time.

SourceDaikin Air Conditioner - Service Manual: RZR-P, RZQ-P(9) Seriesp. 165

Daikin codes Daikin air conditioner codes

Diagnostic procedure

The full U4 procedure

Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.

MyPros+ · DiagnosticsStep 1 preview

First diagnostic step

Check power supply voltage 208-230V; check for wrong wiring, loose terminal, or contact failure in transmission wiring.

SourceDaikin Air Conditioner - Service Manual: RZR-P, RZQ-P(9) Seriesp. 165

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More steps, wiring diagram references, and verified part numbers

Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.

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Where this code is documented

2 manuals in the MyPros+ library document this code for Daikin air conditioner.

Models covered by the manuals that document this code

More models are covered than are listed here.

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The full U4 procedure

Where this code is documented

Models covered by the manuals that document this code

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