SplitAtlas

Error-code hub

ACiQ error codes

ACiQ is built on Midea hardware, and its fault codes are Midea's - the EC, EH, EL and PC families below will match what you would find on a Midea or Senville system. The 36 codes cover the Essentials, Standard and Extreme lines plus the multi-zone series. Codes display on the indoor unit; multi-zone condensers report some codes only at the outdoor board.

See ACiQmini-splits ->Common FirstStatus DisplaysError Codes
Status displays
8
Error codes
36

Unit applicability

Match your unit before reading the table

This table is sourced for Multi-Zone Extreme Series. If your unit is a different generation or product line not named here, the same display code may vary by generation.

Multi-Zone Extreme Series5 models

Common codes first

Most broadly applicable documented codes

Ranking basis: we do not have failure-frequency telemetry. These are ordered by breadth of affected systems in the SplitAtlas catalog - the documented product line's published model count, whether the same code appears on more than one product line, and any manual applicability notes we hold. This is a breadth ranking, not a popularity claim.

EC0D

EC0D is a broad outdoor-unit malfunction display. It tells you the outdoor unit needs diagnosis, but the homeowner display does not name one specific part.

AdvisoryTechnician
Breadth evidence
5 published catalog models on its documented product line. Manual applicability notes: ACiQ Multi-Zone Extreme Series R-454B systems using the shared Midea/ACiQ multi-zone platform.; ACiQ Multi-Zone Standard Series R-454B systems where the ACiQ service manual lists the same EC/EH/EL/PC diagnostics.; ACiQ wall-mounted, cassette, duct, console, and AHU indoor units listed in service manual section 7.2.
Safe first check
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
View the fix
EC07

EC07 means the outdoor unit is not seeing outdoor fan speed in the range it expects. The fan may be blocked, failing, or not being driven correctly.

AdvisoryTechnician
Breadth evidence
5 published catalog models on its documented product line. Manual applicability notes: ACiQ Multi-Zone Extreme Series R-454B systems using the shared Midea/ACiQ multi-zone platform.; ACiQ Multi-Zone Standard Series R-454B systems where the ACiQ service manual lists the same EC/EH/EL/PC diagnostics.; ACiQ wall-mounted, cassette, duct, console, and AHU indoor units listed in service manual section 7.2.
Safe first check
Turn the unit off and look only through the outdoor grille for obvious leaves, snow, or debris. Remove loose debris outside the cabinet, restore power once, and stop if EC07 returns.
View the fix
EC51

EC51 means the outdoor control board is not getting valid feedback from its EEPROM memory. This is not a remote setting or homeowner-adjustable parameter.

AdvisoryTechnician
Breadth evidence
5 published catalog models on its documented product line. Manual applicability notes: ACiQ Multi-Zone Extreme Series R-454B systems using the shared Midea/ACiQ multi-zone platform.; ACiQ Multi-Zone Standard Series R-454B systems where the ACiQ service manual lists the same EC/EH/EL/PC diagnostics.; ACiQ wall-mounted, cassette, duct, console, and AHU indoor units listed in service manual section 7.2.
Safe first check
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
View the fix
EC52

EC52 means the outdoor coil temperature reading is outside the valid electrical range. The system cannot safely judge outdoor coil temperature.

AdvisoryTechnician
Breadth evidence
5 published catalog models on its documented product line. Manual applicability notes: ACiQ Multi-Zone Extreme Series R-454B systems using the shared Midea/ACiQ multi-zone platform.; ACiQ Multi-Zone Standard Series R-454B systems where the ACiQ service manual lists the same EC/EH/EL/PC diagnostics.; ACiQ wall-mounted, cassette, duct, console, and AHU indoor units listed in service manual section 7.2.
Safe first check
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
View the fix
EC53

EC53 means the outdoor ambient-air temperature reading is not believable to the board. The system may stop because it cannot apply outdoor operating limits correctly.

AdvisoryTechnician
Breadth evidence
5 published catalog models on its documented product line. Manual applicability notes: ACiQ Multi-Zone Extreme Series R-454B systems using the shared Midea/ACiQ multi-zone platform.; ACiQ Multi-Zone Standard Series R-454B systems where the ACiQ service manual lists the same EC/EH/EL/PC diagnostics.; ACiQ wall-mounted, cassette, duct, console, and AHU indoor units listed in service manual section 7.2.
Safe first check
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
View the fix
EC54

EC54 means the discharge temperature sensor signal is out of range. The system cannot verify compressor discharge temperature, so it should not be forced to keep running.

AdvisoryTechnician
Breadth evidence
5 published catalog models on its documented product line. Manual applicability notes: ACiQ Multi-Zone Extreme Series R-454B systems using the shared Midea/ACiQ multi-zone platform.; ACiQ Multi-Zone Standard Series R-454B systems where the ACiQ service manual lists the same EC/EH/EL/PC diagnostics.; ACiQ wall-mounted, cassette, duct, console, and AHU indoor units listed in service manual section 7.2.
Safe first check
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
View the fix

Safe first checks

Checks you can do without opening the unit

These codes have homeowner-safe steps such as filters, airflow, condensate/drain checks, remote/controller items, or a single safe power reset. If the code returns, stop at the boundary in the card.

EH03DIY part

Turn the unit off, clean the washable indoor filter, and check only for obvious blockage at the return or outlet. If the filter frame is missing or damaged, replace only the user-removable air filter after verifying your indoor model. Restart once; if EH03 returns, stop there.

Part route noted

No exact ACiQ Multi-Zone Extreme Series parts page in the current catalog has a manufacturer-sourced OEM air filter number yet.

View sourced part route
Read the full code guide
EC0DTechnician

Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.

Read the full code guide
EC07Technician

Turn the unit off and look only through the outdoor grille for obvious leaves, snow, or debris. Remove loose debris outside the cabinet, restore power once, and stop if EC07 returns.

Read the full code guide
EC51Technician

Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.

Read the full code guide

ACiQ mini-splits

Use the ACiQ catalog to connect these manual error codes to current model pages and replacement options.

See ACiQmini-splits ->

Status displays

DF

DF means the outdoor unit is melting frost from the coil during heating. It is normal in cold, damp weather and is not an error code.

Not an error
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Let defrost finish. Steam, water, and a temporary pause in warm air can be normal; operation should return after the cycle clears.
Status note
This is a normal status indication, not an error, unless comfort is poor, water is present, or the indication never clears.
View the fix ->

FC

FC means the outdoor board is in forced cooling or alternating that status with running frequency. It is a service/test status, not a normal repair code.

Not an error
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
If a technician intentionally placed the unit in forced cooling, let them finish. If FC appears during normal use and will not clear, turn the system off once and call for service.
Status note
This is a normal status indication, not an error, unless comfort is poor, water is present, or the indication never clears.
View the fix ->

LC

LC on the outdoor board means the unit is operating in low-ambient cooling mode. It is not the same as a fault code.

Not an error
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
No repair is needed if the system is operating as expected. If cooling is poor, note the outdoor temperature and call for service.
Status note
This is a normal status indication, not an error, unless comfort is poor, water is present, or the indication never clears.
View the fix ->

MODE CONFLICT

On a multi-zone system, one room calling for heating while another calls for cooling can stop one head and show --/---- or a conflict status. That is a control conflict, not a failed part.

Not an error
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Set all connected indoor heads to the same mode, then wait several minutes. Expected result: the conflict clears and zones resume in one shared mode.
Status note
This is a normal status indication, not an error, unless comfort is poor, water is present, or the indication never clears.
View the fix ->

PH

PH on the outdoor board means compressor pre-heating is running before operation. It is a status display, not a failed part.

Not an error
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Leave power applied and wait for the preheat condition to clear, especially in cold weather.
Status note
This is a normal status indication, not an error, unless comfort is poor, water is present, or the indication never clears.
View the fix ->

RO

RO means the system is running an oil-return process to protect compressor lubrication. It is a status display, not a homeowner repair.

Not an error
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Let the process finish. Call for service only if comfort is poor or RO repeats with shutdowns.
Status note
This is a normal status indication, not an error, unless comfort is poor, water is present, or the indication never clears.
View the fix ->

RUNNING FREQUENCY

When the outdoor display shows a changing number during operation, it may be showing compressor frequency or a status readout rather than a fault.

Not an error
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Do not diagnose from the outdoor number alone. Use the indoor display first, or have a technician use the SW1 point-check function.
Status note
This is a normal status indication, not an error, unless comfort is poor, water is present, or the indication never clears.
View the fix ->

SW1 STATUS CHECK

The outdoor SW1 button cycles through connected indoor units, temperatures, EXV positions, fan state, last error, and other service values. Those normal readouts are not standalone errors.

Not an error
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Do not press outdoor-board controls unless you are qualified and the cabinet is safely accessed. Give your technician the indoor display code instead.
Status note
This is a normal status indication, not an error, unless comfort is poor, water is present, or the indication never clears.
View the fix ->

All error codes

ECC1

ECC1 means the leak alarm came from a different indoor head on the same multi-zone system. Treat the whole system as unsafe until a technician verifies the leak sensor and refrigerant circuit.

Stop useTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off, ventilate the space, avoid flames, sparks, and smoking, and do not reset the unit back into normal operation. Expected result: the system stays off until a licensed technician verifies the leak sensor and refrigerant circuit.
When to call a pro
Call a licensed HVAC technician immediately. Tell them the display is ECC1 and that another indoor unit's refrigerant sensor reported leakage.
View the fix ->

EHC1

EHC1 is a refrigerant leak alarm from the indoor refrigerant sensor. Because the system uses R-454B A2L refrigerant, treat this as a stop-use safety event.

Stop useTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off, ventilate the space, avoid flames, sparks, and smoking, and do not reset the unit back into normal operation. Expected result: the system stays off until a licensed technician verifies the leak sensor and refrigerant circuit.
When to call a pro
Call a licensed HVAC technician immediately. Tell them the display is EHC1 and the manual says the refrigerant sensor detected leakage.
View the fix ->

EHC2

EHC2 means the leak-sensor reading is out of range while the system also detects a leakage condition. Treat it as both a leak alarm and a failed safety-sensor condition.

Stop useTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off, ventilate the space, avoid flames, sparks, and smoking, and do not reset the unit back into normal operation. Expected result: the system stays off until a licensed technician verifies the leak sensor and refrigerant circuit.
When to call a pro
Call a licensed HVAC technician immediately. Tell them the display is EHC2 and that it combines leakage detection with refrigerant sensor out-of-range.
View the fix ->

EHC3

EHC3 means the leak-detection sensor cannot be trusted. Even without a confirmed leak alarm, the A2L safety sensor is part of the system's protection strategy.

Stop useTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off, ventilate the space, avoid flames, sparks, and smoking, and do not reset the unit back into normal operation. Expected result: the system stays off until a licensed technician verifies the leak sensor and refrigerant circuit.
When to call a pro
Call a licensed HVAC technician before normal operation. Tell them the display is EHC3 and the refrigerant sensor is out of range.
View the fix ->

EL0C

EL0C means the system thinks refrigerant is missing or leakage is present. On an R-454B A2L system, do not keep clearing this code and running the unit.

Stop useTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off, ventilate the space, avoid flames, sparks, and smoking, and do not reset the unit back into normal operation. Expected result: the system stays off until a licensed technician verifies the leak sensor and refrigerant circuit.
When to call a pro
Call a licensed HVAC technician before using the system normally again. Tell them the display is EL0C and the table says system lacks refrigerant.
View the fix ->

FHCC

FHCC means the refrigerant leak sensor is not working correctly. Because that sensor is part of the R-454B A2L leak-detection system, treat FHCC as stop-use until a pro verifies the safety system.

Stop useTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off, ventilate the space, avoid flames, sparks, and smoking, and do not reset the unit back into normal operation. Expected result: the system stays off until a licensed technician verifies the leak sensor and refrigerant circuit.
When to call a pro
Call a licensed HVAC technician before normal operation. Tell them the display is FHCC and the installation manual says the refrigerant sensor malfunctioned.
View the fix ->

EC07

EC07 means the outdoor unit is not seeing outdoor fan speed in the range it expects. The fan may be blocked, failing, or not being driven correctly.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the unit off and look only through the outdoor grille for obvious leaves, snow, or debris. Remove loose debris outside the cabinet, restore power once, and stop if EC07 returns.
When to call a pro
Call a licensed HVAC technician if the outdoor fan is not visibly blocked, the fan blade is damaged, or EC07 returns. Tell them the code is outdoor fan speed out of control.
View the fix ->

EC0D

EC0D is a broad outdoor-unit malfunction display. It tells you the outdoor unit needs diagnosis, but the homeowner display does not name one specific part.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EC0D returns after one reset. Tell them the indoor display says EC0D and ask them to read the outdoor-board diagnostic before replacing parts.
View the fix ->

EC51

EC51 means the outdoor control board is not getting valid feedback from its EEPROM memory. This is not a remote setting or homeowner-adjustable parameter.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EC51 returns after one reset or appears after a board/service visit. Tell them the manual points to the outdoor EEPROM circuit.
View the fix ->

EC52

EC52 means the outdoor coil temperature reading is outside the valid electrical range. The system cannot safely judge outdoor coil temperature.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EC52 returns after one reset. Tell them the code points to the outdoor coil T3 sensor circuit.
View the fix ->

EC53

EC53 means the outdoor ambient-air temperature reading is not believable to the board. The system may stop because it cannot apply outdoor operating limits correctly.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EC53 returns after one reset. Tell them the code points to outdoor ambient sensor T4.
View the fix ->

EC54

EC54 means the discharge temperature sensor signal is out of range. The system cannot verify compressor discharge temperature, so it should not be forced to keep running.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EC54 returns after one reset. Tell them the code points to compressor discharge sensor T5.
View the fix ->

EC56

EC56 means the system cannot trust the indoor coil outlet temperature sensor located at the outdoor low-pressure valve circuit.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EC56 returns after one reset. Tell them the code points to the evaporator coil outlet T2B sensor circuit.
View the fix ->

EH00

EH00 means the indoor control board is not getting valid feedback from its EEPROM memory. This usually appears after installation, service, or a board fault.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH00 returns after one reset. Tell them the manual points to the indoor EEPROM circuit.
View the fix ->

EH03

EH03 means the indoor blower is not reporting a normal speed. A clogged washable filter or blocked outlet can contribute, but repeated EH03 usually needs motor/board diagnosis.

AdvisoryDIY part
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the unit off, clean the washable indoor filter, and check only for obvious blockage at the return or outlet. If the filter frame is missing or damaged, replace only the user-removable air filter after verifying your indoor model. Restart once; if EH03 returns, stop there.
When to call a pro
Call a licensed HVAC technician if EH03 returns after the filter and visible airflow path are clear, or if the blower does not run normally. Tell them the code is indoor fan speed malfunction.

Part route noted

No exact ACiQ Multi-Zone Extreme Series parts page in the current catalog has a manufacturer-sourced OEM air filter number yet.

View sourced part route
View the fix ->

EH0A

EH0A is another homeowner-facing indoor EEPROM parameter display. It points to the indoor board memory/configuration path, not a remote setting.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH0A returns after one reset or appears after a board replacement. Tell them the manual points to indoor EEPROM feedback.
View the fix ->

EH0B

EH0B means the indoor display and indoor main board are not exchanging signals reliably. The unit may still power up, but the control path is not trustworthy.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH0B returns after one reset. Tell them the code is indoor main-board/display-board communication.
View the fix ->

EH0E

EH0E means the indoor unit thinks condensate water level is unsafe or the water-level alarm circuit is not reading correctly. Do not ignore it because water can overflow from the indoor unit.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the unit off to prevent overflow. If you have an external condensate pump with a visible reservoir, make sure it has power and is not obviously full or blocked. Do not open the indoor cabinet. Restart once only if no water is present.
When to call a pro
Call a licensed HVAC technician if water is present, the alarm returns, or the drain/pump is not plainly external and accessible. Tell them the code is EH0E water-level alarm.
View the fix ->

EH3A

EH3A means an external fan module on applicable indoor units is seeing low DC bus voltage. This is an electrical/module diagnostic, not an airflow setting.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH3A returns after one reset. Tell them it is the external fan module DC bus low-voltage protection.
View the fix ->

EH3B

EH3B means an external fan module on applicable indoor units is seeing high DC bus voltage. This is an electrical/module diagnostic and should not be DIY repaired.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH3B returns after one reset. Tell them it is the external fan module DC bus high-voltage fault.
View the fix ->

EH60

EH60 means the indoor unit cannot trust the room-temperature sensor. Comfort can swing or the unit may stop because it does not know the room temperature accurately.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH60 returns after one reset. Tell them the code points to indoor room sensor T1.
View the fix ->

EH61

EH61 means the indoor evaporator coil temperature sensor is out of range. The system cannot protect the indoor coil accurately.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH61 returns after one reset. Tell them the code points to indoor coil sensor T2.
View the fix ->

EH62

EH62 means an evaporator coil inlet temperature sensor circuit is open or shorted on applicable indoor units. The system cannot safely use that coil-temperature reading.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH62 returns after one reset. Tell them the code points to the AHU/indoor evaporator T2B sensor circuit.
View the fix ->

EH65

EH65 means the T2A evaporator coil inlet temperature sensor circuit is not reading correctly on applicable indoor units.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH65 returns after one reset. Tell them the code points to evaporator coil inlet sensor T2A.
View the fix ->

EH66

EH66 is another display for an evaporator coil inlet temperature sensor open/short condition. Treat it as the same homeowner issue as EH62: a sensor circuit needs service.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EH66 returns after one reset. Tell them Table 20 groups EH62/EH66 as evaporator coil inlet T2B open/short.
View the fix ->

EHB3

EHB3 means a wired controller or master-control communication path is not being read correctly. It is not fixed from normal remote settings.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EHB3 returns after one reset. Tell them the code is communication error between wired control and master control.
View the fix ->

EHBA

EHBA applies to certain cassette/external-fan configurations. It means the indoor unit is not receiving expected feedback from the external fan module.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EHBA returns after one reset. Tell them it is an indoor/external-fan-module communication fault.
View the fix ->

EL01

EL01 means at least one indoor unit and the outdoor unit are not exchanging control signals reliably. The two sides of the system cannot coordinate normal operation.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EL01 returns after one reset, appears on a new installation, or affects multiple zones. Tell them the code is indoor/outdoor communication.
View the fix ->

EL16

EL16 means the outdoor main board is not getting expected feedback from an adapter board on applicable units. This is a wiring/board communication issue.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if EL16 returns after one reset. Tell them the code is adapter board to outdoor main board communication.
View the fix ->

FL09

FL09 means the equipment or control platform combination does not match what the system expects. This is most likely an installation, replacement-board, or compatibility issue.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if FL09 appears. Tell them the display says mismatch between new and old platforms and give them the indoor and outdoor model numbers.
View the fix ->

PC00

PC00 means the outdoor inverter power module reported an abnormal compressor-drive condition. It can shut the system down to protect expensive electronics and the compressor.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if PC00 returns after one reset. Tell them the code is outdoor IPM module protection.
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PC01

PC01 means the outdoor unit saw supply voltage or DC bus voltage outside the expected range. It may be a utility/brownout issue, wiring issue, or outdoor-board fault.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off and note whether lights dimmed, storms occurred, or other appliances had power trouble. Reset once only after power is stable. If PC01 returns or any breaker trips, stop there.
When to call a pro
Call a licensed HVAC technician or electrician if PC01 returns, a breaker trips, or other circuits show voltage trouble. Tell them the code is outdoor voltage protection.
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PC02

PC02 means the system protected the compressor top or inverter module from high temperature. Dirty airflow can contribute, but repeated PC02 can point to sealed-system, compressor, or board problems.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off, clean indoor filters, and clear only loose debris around the outdoor unit without removing panels. Restore power once after the unit has cooled; if PC02 returns, stop using it.
When to call a pro
Call a licensed HVAC technician if PC02 returns after airflow is corrected. Tell them the code is compressor top/IPM temperature protection.
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PC03

PC03 means the refrigerant pressure protection circuit opened on either low or high pressure. This is sealed-system diagnosis, not a code to keep clearing.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the unit off, make sure filters and outdoor airflow are not obviously blocked, and reset once only. Do not attach gauges or add refrigerant.
When to call a pro
Call a licensed HVAC technician if PC03 returns. Tell them the display is pressure protection and note whether it happened in heating or cooling.
View the fix ->

PC04

PC04 means the outdoor inverter drive could not operate the compressor normally. This can involve the compressor, IPM, outdoor board, or drive wiring.

AdvisoryTechnician
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Turn the system off with the remote, then power cycle once at the breaker or disconnect if you can do that safely. Expected result: a temporary control fault clears; if the code returns, stop resetting and schedule service.
When to call a pro
Call a licensed HVAC technician if PC04 returns after one reset or the outdoor unit will not start. Tell them the code is inverter compressor drive error.
View the fix ->

PC0L

PC0L means the system is protecting itself because outdoor conditions are below the allowed operating range for that mode. This is usually an operating-limit condition, not a failed part.

AdvisoryDIY
Sourced Jul 2026
Applies to
Multi-Zone Extreme Series
Homeowner fix
Leave power applied to the outdoor unit and wait for outdoor conditions to return inside the unit's operating range. Expected result: the code clears when conditions allow normal operation.
When to call a pro
Call a licensed HVAC technician if PC0L appears in mild weather, will not clear after conditions improve, or the system is being asked to cool/heat in conditions it should support.
View the fix ->