Haier Aircon 21 Error Code
Use this Haier 21 error code guide to confirm the source table meaning, capture the reporting equipment and model, and match the service manual before diagnosis. Match the model first; same-looking codes can point to different rows.
What does Haier 21 mean?
Haier 21 is listed as outdoor ambient-temperature sensor Ta failure, indoor pipe-temperature too-low protection, and compressor discharge-temperature sensor Td abnormality in MRV-S MVHP outdoor unit, S2 R32 split-system outdoor unit, FlexFit Pro large cassette, MRV5 AV08-AV26IMVEVA - outdoor failure table, and 2024 1U90-1U160 S2 outdoor units source rows. The loaded row is source-backed by official diagnostic material. Do not collapse this code across model families; use the model, series, or system type to choose the right row. Confirm the exact model, series, or signal row before accepting a parts quote.
Choose the matching source row
The same visible code has more than one source-backed meaning. Match the model family, system type, or reporting unit before approving parts.
| Code | What it means | What to check first |
|---|---|---|
| MRV-S MVHP outdoor unit | Outdoor ambient-temperature sensor Ta failure | Match this row to the installed model or reporting unit, then use the source-specific checks below. |
| S2 R32 split-system outdoor unit / 2024 1U90-1U160 S2 outdoor units | Indoor pipe-temperature too-low protection | Match this row to the installed model or reporting unit, then use the source-specific checks below. |
| FlexFit Pro large cassette | Compressor discharge-temperature sensor Td abnormality | Match this row to the installed model or reporting unit, then use the source-specific checks below. |
| MRV5 AV08-AV26IMVEVA - outdoor failure table | Ambient temperature sensor Ta failure | Match this row to the installed model or reporting unit, then use the source-specific checks below. |
- Code
- MRV-S MVHP outdoor unit
- What it means
- Outdoor ambient-temperature sensor Ta failure
- What to check first
- Match this row to the installed model or reporting unit, then use the source-specific checks below.
- Code
- S2 R32 split-system outdoor unit / 2024 1U90-1U160 S2 outdoor units
- What it means
- Indoor pipe-temperature too-low protection
- What to check first
- Match this row to the installed model or reporting unit, then use the source-specific checks below.
- Code
- FlexFit Pro large cassette
- What it means
- Compressor discharge-temperature sensor Td abnormality
- What to check first
- Match this row to the installed model or reporting unit, then use the source-specific checks below.
- Code
- MRV5 AV08-AV26IMVEVA - outdoor failure table
- What it means
- Ambient temperature sensor Ta failure
- What to check first
- Match this row to the installed model or reporting unit, then use the source-specific checks below.
How this fault may be shown
Match every scope item the source provides—exact model where listed, PCB or panel where listed, and reporting device—before using a displayed value. These manufacturer crosswalks are display evidence, not universal codes or repair instructions.
Split outdoor control board - 1U105 SSModels 1U105S2SS1FA, 1U105S2SS2FA · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 20
| Reported by | Shown as |
|---|---|
| Outdoor control-board diagnostic display | 21 |
- Reported by
- Outdoor control-board diagnostic display
- Shown as
- 21
Split outdoor control board - 1U125 SN / 1U140 SPModels 1U125S2SN1FA, 1U125S2SN1FB, 1U140S2SP1FA, 1U140S2SP1FB · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 20
| Reported by | Shown as |
|---|---|
| Outdoor control-board diagnostic display | 21 |
- Reported by
- Outdoor control-board diagnostic display
- Shown as
- 21
Low-static duct PCB 0151800267 LED4 / LED3PCB 0151800267 · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 21
| Reported by | Shown as |
|---|---|
| Low-static duct TIMER LED4 and RUNNING LED3 | LED4 4 / LED3 1 |
- Reported by
- Low-static duct TIMER LED4 and RUNNING LED3
- Shown as
- LED4 4 / LED3 1
Low/medium-static duct PCB 0151800644 LED4 / LED3PCB 0151800644 · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 21
| Reported by | Shown as |
|---|---|
| Low/medium-static duct TIMER LED4 and RUNNING LED3 | LED4 4 / LED3 1 |
- Reported by
- Low/medium-static duct TIMER LED4 and RUNNING LED3
- Shown as
- LED4 4 / LED3 1
Low/medium-static duct panel on PCB 0151800644PCB 0151800644 · Panels P1B-890IA/D, P1B-1210IA/D · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 21
| Reported by | Shown as |
|---|---|
| Low/medium-static duct panel display | F21 |
- Reported by
- Low/medium-static duct panel display
- Shown as
- F21
AC ceiling/floor TIMER LED6 / RUNNING LED1Models AC35S2SG1FA, AC50S2SG1FA, AC71S2SG1FA, AC90S2SH1FA, AC105S2SH1FA, AC125S2SK1FA, AC140S2SK1FA, AC160S2SK1FA · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 23
| Reported by | Shown as |
|---|---|
| AC ceiling/floor TIMER LED6 and RUNNING LED1 | LED6 4 / LED1 1 |
- Reported by
- AC ceiling/floor TIMER LED6 and RUNNING LED1
- Shown as
- LED6 4 / LED1 1
AC ceiling/floor displayModels AC35S2SG1FA, AC50S2SG1FA, AC71S2SG1FA, AC90S2SH1FA, AC105S2SH1FA, AC125S2SK1FA, AC140S2SK1FA, AC160S2SK1FA · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 23
| Reported by | Shown as |
|---|---|
| AC ceiling/floor display | F21 |
- Reported by
- AC ceiling/floor display
- Shown as
- F21
AF floor TIMER LED6 / RUNNING LED1Models AF25S2SD1FA, AF35S2SD1FA, AF42S2SD1FA · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 24
| Reported by | Shown as |
|---|---|
| AF floor TIMER LED6 and RUNNING LED1 | LED6 4 / LED1 1 |
- Reported by
- AF floor TIMER LED6 and RUNNING LED1
- Shown as
- LED6 4 / LED1 1
AF floor displayModels AF25S2SD1FA, AF35S2SD1FA, AF42S2SD1FA · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 24
| Reported by | Shown as |
|---|---|
| AF floor display | F21 |
- Reported by
- AF floor display
- Shown as
- F21
Source-labelled cassette TIMER / RUNNING LEDsSource-labelled equipment family; exact models are not listed in this table · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 25
| Reported by | Shown as |
|---|---|
| Cassette TIMER and RUNNING LEDs | TIMER 4 / RUNNING 1 |
- Reported by
- Cassette TIMER and RUNNING LEDs
- Shown as
- TIMER 4 / RUNNING 1
Source-labelled cassette displaySource-labelled equipment family; exact models are not listed in this table · Haier Split and Multi Split Error Codes, version 01/2024, PDF page 25
| Reported by | Shown as |
|---|---|
| Cassette display | 29 |
- Reported by
- Cassette display
- Shown as
- 29
What to do now
Use these steps to record evidence and match the installed model to its service manual before diagnosis or a repair quote.
Record 21 and match the service manual
Record 21 and stop there; the source table gives no customer reset procedure. Arrange diagnosis with the matching service manual.
No manufacturer reset steps listed for 21
Capture the complete 21 error code and model stickers first. The source table lists the meaning but no customer reset procedure; do not treat a generic power-cycle as manufacturer guidance.
Send these to us
21 error code, a clear display photo, Haier indoor and outdoor model stickers, the controller, gateway, or unit that reported the code, operating mode and affected area, and any power or setting changes made after the code appeared
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 |
|---|---|
| Singapore / model note | Official Haier America MRV-S MVHP service-manual row. Confirm the exact MVHP outdoor model and reporting display; no universal Singapore-model parity is claimed. |
| Singapore / model note | Official Haier Australia S2 split-system manual row. Confirm the exact 1U S2 outdoor model before using the meaning; no universal Haier-model parity is claimed. |
| Singapore / model note | Official Haier Appliances FlexFit Pro large-cassette display decoder. The source converts an outdoor decimal fault to the hexadecimal code flashed indoors; the exact display identity is retained. Match the named model family before diagnosis. |
- Source detail
- Singapore / model note
- What it says
- Official Haier America MRV-S MVHP service-manual row. Confirm the exact MVHP outdoor model and reporting display; no universal Singapore-model parity is claimed.
- Source detail
- Singapore / model note
- What it says
- Official Haier Australia S2 split-system manual row. Confirm the exact 1U S2 outdoor model before using the meaning; no universal Haier-model parity is claimed.
- Source detail
- Singapore / model note
- What it says
- Official Haier Appliances FlexFit Pro large-cassette display decoder. The source converts an outdoor decimal fault to the hexadecimal code flashed indoors; the exact display identity is retained. Match the named model family before diagnosis.
What to check before repair
The source table establishes the code meaning, not a repair procedure. Capture evidence first; model-specific tests belong to the matching service manual.
| You can check | Technician should confirm |
|---|---|
| Photograph the complete 21 error code before taking any action. | Confirm 21 exactly and record which controller, gateway, or unit reported it. |
| Capture the Haier indoor and outdoor model stickers and identify which controller or unit reported it. | Match the indoor and outdoor model stickers, installed family, and reporting equipment to the source scope. |
| The source table provides no customer reset procedure. Preserve the evidence and use the matching service manual for any system action. | Follow the matching service-manual procedure and keep measured test evidence before naming a failed part. |
- You can check
- Photograph the complete 21 error code before taking any action.
- Technician should confirm
- Confirm 21 exactly and record which controller, gateway, or unit reported it.
- You can check
- Capture the Haier indoor and outdoor model stickers and identify which controller or unit reported it.
- Technician should confirm
- Match the indoor and outdoor model stickers, installed family, and reporting equipment to the source scope.
- You can check
- The source table provides no customer reset procedure. Preserve the evidence and use the matching service manual for any system action.
- Technician should confirm
- Follow the matching service-manual procedure and keep measured test evidence before naming a failed part.
Source-bounded repair decision
Haier 21 confirms the source-table fault label, not a failed part or repair procedure. Match the installed model to its service manual and require measured diagnostic evidence before approving parts, settings, or refrigerant work.
Whether the reporting controller or unit and exact installed model are confirmed.
What the matching service-manual procedure and measured tests show.
Whether the proposed repair names the evidence for the failed part or condition.
Haier 21 questions
What does the Haier 21 error mean?
Can I fix a Haier 21 error myself?
Is it safe to keep running the aircon with a 21 error?
What causes a Haier 21 error?
Will a Haier 21 error need a repair or a full replacement?
What should I send a technician about a Haier 21 error?
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Use this quote-check guide only after the matching service manual identifies the diagnostic path.