What It Means
H3 fires when the high pressure switch (HPS) circuit itself is found faulty — an open circuit, broken wire, or bad connector — as opposed to E3, which trips when the HPS correctly detects an actual high-pressure event.
Daikin Split & Multi-Split
Daikin Split & Multi-Split Error Code H3
Troubleshooting guide for the Daikin Split & Multi-Split system fault H3.
Possible Causes
- High pressure switch contacts failed open or welded shut.
- Broken or frayed wire between the HPS and outdoor unit PCB.
- Corroded or loose HPS connector.
- Defective outdoor unit PCB input circuit for the HPS.
- Physical damage to the switch from vibration or impact during installation or transport.
Not sure which one it is — or if it's none of these? Try ACLogics today.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis
H3 fires when the high pressure switch (HPS) circuit itself is found faulty — an open circuit, broken wire, or bad connector — as opposed to E3, which trips when the HPS correctly detects an actual high-pressure event. H3 takes the whole outdoor unit offline as a safety precaution since the controller can no longer trust pressure-side protection, and on a multi-split this stops every indoor unit sharing that outdoor unit. Unlike H0, H1, or H5 (which involve compressor sensors and overload thermistors), H3 is specific to the high-pressure switch wiring and contact integrity.
All Recorded Causes
High pressure switch contacts failed open or welded shut. Broken or frayed wire between the HPS and outdoor unit PCB. Corroded or loose HPS connector. Defective outdoor unit PCB input circuit for the HPS. Physical damage to the switch from vibration or impact during installation or transport.
Verify Before Replacing Parts
- Confirm the exact Daikin model family and split/ multi split context before acting on a generic code description.
- Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge, since high pressure switch contacts failed open or welded shut.
- Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm broken or frayed wire between the HPS and outdoor unit PCB.
- After the correction, run the system long enough to confirm the split/ multi split fault does not return under normal load.
Still unsure about this fault?
ACLogics walks you through Daikin Split & Multi-Split diagnostics step-by-step — so you confirm the cause before swapping parts.
