Daikin VRV 5 Heat Recovery aircon CH-21 error code
Use this Daikin VRV 5 Heat Recovery CH-21 error code guide to capture the fault correctly and see what should be checked before parts are quoted.
What does Daikin CH-21 mean?
Daikin VRV 5 Heat Recovery CH-21 is listed as r32 sensor malfunction in a BS unit in VRV 5 Heat Recovery REMA / REYA R32 source row. The loaded row is source-backed by official diagnostic material. Confirm the exact model, series, or signal row before accepting a parts quote.
Open, shorted, displaced, or out-of-range thermistor or pressure-sensor reading.
Loose sensor connector, damaged sensor harness, or water-affected wiring.
PCB input fault after the sensor and wiring readings are confirmed.
What to do now
Use these steps before customer action, a sensor check, or PCB quote.
Stop using the unit if CH-21 returns
Do not keep resetting CH-21; record the code and arrange diagnosis using the matching model-family table.
Do not reset CH-21 from this table
Capture the CH-21 display and model sticker first. Record the complete code, reporting unit, serial number, and model sticker, then arrange qualified Daikin diagnosis. Do not treat a generic power-cycle as a manufacturer reset procedure.
Send these to us
CH-21 error code, a clear display photo, Daikin VRV 5 Heat Recovery model stickers, affected rooms, operating state when the code appeared, and when the fault appears
Source-specific guidance
These diagnostic-reference notes help match the code to the exact model. Electrical, refrigerant, wiring, resistance, and component checks are technician work, not DIY steps.
| Source detail | What it says |
|---|---|
| Diagnostic note | Check the BS-unit R32 sensor connection at the PCB or actuator. |
| Singapore / model note | Official Daikin 4P687640-1D row for the REMA5A7Y1B and REYA8~20A7Y1B VRV 5 Heat Recovery R32 family. Confirm the exact model and displayed punctuation before using this interpretation. |
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 taking any action on CH-21, take a clear display photo. | Confirm which sensor CH-21 maps to on the exact model table. |
| Capture the Daikin VRV 5 Heat Recovery model sticker and identify which controller or unit reported the code. | Measure the sensor value against the service-manual resistance or voltage range. |
| Record the complete code, reporting unit, serial number, and model sticker, then arrange qualified Daikin diagnosis. | Check connector condition, harness continuity, and PCB input before replacing boards. |
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 CH-21. | The affected room, indoor board path, wiring route, or local component should be checked first. |
| Several rooms or the outdoor unit show the same CH-21 fault. | Prioritise the reporting-unit sensor circuit, shared harness path, and control-board input. |
| The fault appears immediately even before the unit cools properly. | Sensor value, connector, harness, and PCB input should be tested in that order. |
| 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 VRV 5 Heat Recovery REMA / REYA R32 source row. | The loaded row is source-backed by official diagnostic material. Use the matching source row before quoting parts. |
Sensor or PCB decision
Daikin VRV 5 Heat Recovery CH-21 is usually repair-first if a sensor or harness reading is confirmed. Board replacement should wait until the sensor circuit is tested.
Sensor replacement is usually targeted when resistance or voltage readings are out of range.
Harness or connector damage can look like a sensor fault until continuity is checked.
PCB replacement is a later step if the sensor and wiring test correctly.
Daikin CH-21 questions
What does the Daikin CH-21 error mean?
Can I fix a Daikin CH-21 error myself?
Is it safe to keep running the aircon with a CH-21 error?
What causes a Daikin CH-21 error?
Will a Daikin CH-21 error need a repair or a full replacement?
What should I send a technician about a Daikin CH-21 error?
Confirm the fault
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Use these if the quote mentions the parts, checks, or repair path this code points to.