Daikin aircon C1 error code
Use this Daikin C1 error code guide to decide when to stop resetting, what to capture, and what to check before parts are quoted.
What does Daikin C1 mean?
Daikin C1 is listed as failure of transmission between indoor PCB and sub PCB in Ceiling Cassette, Ceiling Suspended, Residential Ducted rows such as SkyAir, VRV. The loaded row is source-backed by official diagnostic material. Confirm the exact model, series, or signal row before accepting a parts quote.
Loose, corroded, crossed, or damaged indoor-outdoor signal wiring.
Terminal block, connector, or junction fault on the indoor or outdoor side.
Indoor or outdoor PCB communication circuit fault after wiring is proven sound.
What to do now
Use these steps before another reset, signal-wire check, or PCB quote.
Stop using the unit if C1 returns
If C1 returns after one reset, stop repeated restarts and get the matching source row diagnosed.
Reset C1 once
Capture the C1 display first, then power-cycle once only and note whether the same fault returns.
Send these to us
C1 error code, a clear display photo, Daikin model stickers, affected rooms, reset result, and whether one room or every room failed
What to check before repair
Use this split to separate safe evidence capture from the tests a technician should prove before quoting parts.
| You can check | Technician should confirm |
|---|---|
| Before resetting C1, take a clear display photo. | Match C1 against the exact model-family source row before quoting parts. |
| Capture the Daikin indoor and outdoor model stickers so the correct family row is used. | Test communication terminals, cable continuity, polarity, and outdoor power. |
| Note whether one room, several rooms, or the whole system is affected, plus whether it returns after one reset. | Read indoor and outdoor PCB indicators only after the signal path is proven sound. |
What changes the next step
These clues decide whether the first check is room-side, shared outdoor-side, refrigerant-side, source-table, or model-family confirmation.
| What you see | What it points to |
|---|---|
| Only one indoor unit shows C1. | The affected room, indoor board path, wiring route, or local component should be checked first. |
| Several rooms or the outdoor unit show the same C1 fault. | The shared outdoor side, power path, communication trunk, or refrigerant circuit needs priority checking. |
| The fault returns immediately after one reset. | Start with the source-row diagnostic branch before approving parts. |
| The model family is different from the row you found online. | Use the model or series filter first; same-looking codes can still belong to different diagnostic tables. |
| The model belongs to Ceiling Cassette, Ceiling Suspended, Residential Ducted rows such as SkyAir, VRV. | The loaded row is source-backed by official diagnostic material. Use the matching source row before quoting parts. |
Wiring or PCB decision
Daikin C1 should start with terminal, signal-cable, and power checks. PCB replacement only makes sense after the communication path is proven sound.
A loose terminal or bad junction is a targeted repair once the path is confirmed.
Signal-wire replacement depends mostly on access through trunking, ceiling, or concealed routes.
PCB cost should be weighed against age only after wiring and power checks pass.
Read next
Use these if the quote mentions the parts, checks, or repair path this code points to.
Other Daikin error codes
If the code you're seeing isn't C1, jump to one of these or browse the full Daikin list.
Ready to get started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.