Lennox air conditioners provide codes of errors due to the presence of the self-diagnostics function. This option is present in the majority of modern air conditioners. It allows to detect a problem more quickly, using only operating instructions. In a number of cases, the user can remove a malfunction and start the system without calling specialists from a service center and having saved money and time on his own. You can find Error codes of Lennox air conditioners in the tables below.
Air conditioners Lennox LNIV2610 are room air conditioning equipment. They are of inverter split-type. There are indoor and outdoor units. Besides cooling and heating, some models can possess many useful function including ionizer function.
| Display | LED STATUS |
| EO | EEPROM parameter error |
| E1 | Indoor/outdoor units communication protection |
| E2 | Zero-crossing signal error |
| E3 | Indoor fan speed out of control |
| E5 | Open or short circuit of outdoor temperature sensor or outdoor unit EEPROM parameter error |
| E6 | Open or short circuit of room or evaporator temperature sensor |
| E 7 | Outdoor fan speed out of control |
| PO | IBM malfunction or IGBT over-strong current protection |
| P1 | Over voltage or too low voltage protection |
| P2 | Temperature protection of compressor top |
| P4 | Inverter compressor drive error |
Air conditioners Lennox MPA012S4S-1L are mini-split systems possessing DC inverter control. They include units of different types: MPA single zone condensing units, MPA multi-zone condensing units, M22A compact cassette units, MMDA ducted units, MWMA wall mounted units, MCFA ceiling/floor units. Usually, such products have seven-year limited warranty for their compressor and five year- limited warranty- for all other components.
| DISPLAY | OUTDOOR UNITERROR CODE DEFINITION |
| EO | Outdoor EEPROM error |
| E2 | Communication error between outdoor unit and all indoor units |
| E3 | Communication error between outdoor unit main control and IPM control |
| E4 | Temp, sensor error (outdoorcoil sensor, outdoor ambient sensor, compressor discharge sensor, indoor unit coil outlet temp, sensor) |
| E5 | High or Low voltage protection |
| E8 | Outdoor DC fan speed error |
| F1 | Indoor unit#1 coil outlet temp, sensor error |
| F2 | Indoor unit#2 coil outlet temp, sensor error |
| F3 | Indoor unit#3 coil outlet temp, sensor error |
| F4 | Indoor unit #4 coil outlet temp, sensor error |
| F5 | Indoor unit#5 coil outlet temp, sensor error |
| F6 | Indoor unit#6 coil outlet temp, sensor error |
| P1 | High pressure switch open |
| P2 | Low pressure switch open |
| P3 | Outdoor Compressor current overload sensed |
| P4 | High temperature sensed at compressor discharge line |
| P5 | High temperature sensed at outdoor coil |
| Lpe | Inverter module (IPM) error ^ |
Air conditioners Lennox MS8 SERIES include from MS8 series to mini-split single-zone systems for cooling and heating. There are indoor and outdoor units. Remote control of air conditioners is available.
| Display | Yellow | Red | Green | Error Description | System Status | Troubleshooting for Possible Causes |
| NONE | 1 | OFF | OFF | Compressor has an open circuit. | All system functions are terminated except indoor fan. | • Check connections between com- pressor and outdoor control (con- trol terminals are marked U, V and W). |
| OFF | 11 | Frequency limiting module temperature | All system functions are terminated except indoor fan. | • Verify proper attachment of heat sink. | ||
| • Clean heat sink, if necessary. | ||||||
| NONE | OFF | 13 | OFF | Power issue | Compressor speed automatically adjusted to match conditions. | System power issue. |
| C5 | OFF | Indoor control jumper is missing (labeled JUMP) | All system functions are terminated. | • Check indoor control jumper con- nections and replace jumper, if missing. | ||
| EE | 11 | EEPROM failure | • Replace outdoor control. | |||
| E2 | 3 | Indoor coil freeze protection | All system functions are terminated except indoor fan. The indoor coil sensor (RT2) monitors the coil temperature continuously. If coil temperature drops below 30.2°F (-1°C). the compressor and the outdoor fan (30 seconds later) are switched off. Condition is cleared when indoor coil temperature rises above 42.8°F (6°C) and the compressor has been off for a minimum of three minutes. | • Check for restricted indoor airflow and change filter, if necessary. | ||
| • Check for restricted refrigerant flow. | ||||||
| • Check for low outdoor ambient temperature or low indoor system load. | ||||||
| E3 | OFF | 9 | OFF | Outdoor coil blockage or low refrigerant due to leak. | All system functions are terminated except indoor fan. | • Check for proper clearances around outdoor unit. |
| • Check outdoor coil for and clean, if necessary. | ||||||
| E4 | 7 | OFF | OFF | Discharge line temperature protection | Sensor RT5 monitors compressor discharge line temperature and communicates with outdoor unit microprocessor. Depending on the temperature measured, the compressor speed will be increased to meet the load or will continue to run at the existing speed. If the temperature becomes excessively high, the compressor will be de-energized. When the compressor discharge temperature drops below 1&4°F (90°C). the unit will resume normal operation. | • Check for low refrigerant charge. |
| • Check for restricted refrigerant flow due to blocked capillary. | ||||||
| E5 | 5 | OFF | OFF | Compressor over-current protection | All system functions are terminated except indoor fan. | • Check for locked compressor rotor due to excessively high ambient temperature. |
| • Check for restricted refrigerant flow due to blocked capillary tubing. | ||||||
| • Check outdoor unit to make sure that coil is not blocked. | ||||||
| E6 | OFF | OFF | OFF | Communication failure between indoor unit and outdoor unit | All system functions are terminated after three-minute delay except indoor fan. | • If error is displayed on outdoor unit, check communications cable / wire at indoor and outdoor controls to verify proper connection. |
| FH | 4 | Anti-freezing upper and lower limit range | Compressor will run at reduced speed until temperature increases. | • Wait for temperature to increase above 42.8°F (6°C). then recheck operation status. | ||
| FO | OFF | Indoor coil is gathering refrigerant | All system functions are terminated except indoor fan. | • Pump refrigerant into outdoor unit Check 2-way shut-off valve in small line to see if it is closed or if flow is restricted. Correct, if necessary. | ||
| F1 | Indoor ambient sensor (RT1)open or short circuited | Cooling and dehumidification modes will continue to operate as well as indoor fan. Unit will not operate in heating mode. | • Check sensor to ensure that it is in acceptable range. | |||
| • Check sensor for proper resistance. | ||||||
| • Replace sensor if shorted, open or out-of-calibration. | ||||||
| F2 | OFF | OFF | OFF | Indoor coil sensor (RT2) open or short circuited | ||
| F3 | 6 | Outdoor ambient sensor (RT4)open or short circuit | All system functions are terminated except indoor fan. | • Check sensor to ensure that it is in acceptable range. | ||
| • Check sensor for proper resistance. | ||||||
| • Replace sensor if shorted, open or out-of-calibration. | ||||||
| F4 | OFF | 4 | OFF | Outdoor coil sensor (RT3) open or short circuit | ||
| F5 | 7 | Discharge line sensor (RT5) error | All system functions will continue to run for 3 minutes, then terminate. Indoor fan will continue to run. | • Check sensor for proper resistance. Sensor should be in acceptable range. Replace sensor if shorted, open or out-of-calibration. | ||
| F6 | 3 | Compressor over- load limit issue | Normal operational state with compressor speed automatically adjust for operational conditions. System will continue to operation at reduced compressor speed until issue is corrected. | • Check outdoor ambient air temperature. Could be too high. | ||
| • Check for locked compressor rotor. | ||||||
| • Check for blocked refrigeration circuit (capillary tubes for example). | ||||||
| • Check for blocked or restricted outdoor air flow. Clear, if necessary. | ||||||
| • Check for low refrigerant charge. | ||||||
| F8 | OFF | 1 | OFF | High current limit issue | System will continue to operate at reduce compressor speed until issue is corrected. | • Check for low or high input voltage. Correct if necessary. Could be too high. |
| F9 | 2 | Discharge line temperature too high | • Check discharge line temperature. Correct if to high. | |||
| HC | 14 | OFF | Power factor correction protection | System will continue to operate at reduce compressor speed until issue is corrected. | ||
| H1 | 2 | Defrosting (heat pump troubleshooting) | Normal operation | Normal defrost operation. | ||
| H3 | 8 | Compressor overload protection sensor (CT1.2) malfunction. | All system functions are terminated except indoor fan. | • Check for proper wiring connec- tions and loose wires at outdoor control (CT1,2) input plug. | ||
| • Check for continuity across over- load protection sensor terminals mounted at top of compressor. | ||||||
| H4 | 6 | OFF | OFF | Compressor high temperature protection | All system functions are terminated except indoor fan. | • Check for proper wiring connec- tions and loose wires at outdoor control (CT1, 2) input plug. |
| • Check for continuity across over- load protection sensor terminals mounted at top of compressor. | ||||||
| H5 | 4 | OFF | OFF | Intelligent Power Module (IPM) module protection | This can be caused by any of the fol- lowing: | |
| • Loss of cooling to the heat sink | ||||||
| • Low voltage. | ||||||
| • High ambient temperature | ||||||
| • Loose screws fastening the outdoor control to the heat sink | ||||||
| H6 | OFF | OFF | OFF | Indoor fan not communicating | All system functions are terminated. | Possible Indoor control failure or in- door motor failure. |
| • Check wiring between fan motor and indoor control. | ||||||
| • Check wiring between fan motor and terminal marked OF FAN. | ||||||
| • Replace one or both, if necessary. | ||||||
| LP | 16 | OFF | OFF | Indoor and outdoor unit mismatch | The two system components are mis-matched. Also, verify that the red jumper is in place on the indoor control board. | |
| L3 | OFF | 14 | OFF | Outdoor DC fan motor malfunction | • Check wiring between fan motor and outdoor control terminal marked OF FAN. | |
| • If wiring is correct, replace outdoor DC fan motor. | ||||||
| L9 | 9 | OFF | OFF | Power factor protection | Indoor unit is experiencing either a high or low input voltage condition. • Verify proper input voltage at terminal strip N(1) and 3. | |
| PH | 13 | OFF | OFF | High voltage protec- tion | All system functions are terminated. | • Check input voltage on outdoor unit terminal strip (N and L terminals). |
| • If voltage is higher than 265VAC. disconnect power to unit Correct input voltage problem before reap- plying power to system. | ||||||
| • If voltage is below 265VAC. then check capacitor while unit is turned off. | ||||||
| • If voltage is between 200-208V. ca- pacitor is working properly | ||||||
| • If voltage is some other value, re- place capacitor. | ||||||
| • If input voltage and capaator are normal, replace outdoor control. | ||||||
| PL | 12 | OFF | OFF | Low voltage protec- tion | All system functions are terminated. | • Check input voltage on outdoor unit terminal strip (N and L terminals). |
| • If voltage is lower than 150VAC. restart system and check power again. | ||||||
| •9-12 kBtu. 208-230VAC systems only Check reactor (choke) line connection on outdoor control terminal marked AC-L2. |