Indoor unit flashes 5 times. error code meaning?

Called Flash Codes. First try turning off everything at the breaker for at least 2 hours and preferably overnight. Turn back on and wait 15 minutes for self test to complete.

https://www.orionair.co.uk/PDF/fujitsu-trouble-shooting.pdf

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check capacitors to compressor

Could your letter be a F instead of a P?

F3 Indoor unit.
Red LED, Outdoor flashing 6 times. (Outdoor Ambient Sensor)
F4, Indoor unit.
Red LED, Outdoor flashing 5 times. (Outdoor Coil Sensor)

According to an LG installation manual for the LMU540HV, if the flashing light is viewed on the indoor unit with the ceiling cassette light on the far right flashing 5 times, it is an error code meaning there is a communication error between indoor and outdoor units. I would start by making all indoor and the outdoor units have power. I would especially check to see that fuses or circuit breakers to the outdoor unit have not failed. Or check the outside disconnect to make sure it is working. Check with a volt meter to be sure you have 220 volts present to the outdoor unit. Also, if the 4 indoor units have emergency power off switches, make sure all 4 are turned on. Checking to see power is present both indoors and outdoors a good place to start. It the outdoor unit has power, there may be a relay that has failed or a power circuit board has failed that would cause it not to communicate.

Full list of Gree Air Conditioner Mini Split Units Fault Codes. When error codes appear on the Gree air conditioner indoor display, this tells the user there is an issue with the Gree AC unit. The error code displayed will inform you of the issue or problem that is occurring with the air conditioner. Knowing what the error code means and its definition will help you to understand and troubleshoot the exact Gree air conditioner part that needs to be fixed, cleaned, repaired, or replaced. You can then clean, fix, or replace the Gree part yourself and save money. See below for all error codes that can occur on Gree Mini Split AC's.
Gree Mini Split Air Conditioner Error Codes - How To Fix
Gree Viero AC Mini Split PDF Owners and Troubleshooting Manual
GREE DUCTLESS AIR CONDITIONING & HEATING SYSTEM INSTALLATION MANUAL

Gree Mini Split Air Conditioner Part Names and Locations
INDOOR AND OUTDOOR UNIT
The Gree Air Conditioning Vireo System has onboard error code diagnostics. The outdoor unit will provide status indicators and the indoor wall unit and remote control will display error codes. The following is a summary of the codes with explanations...
GREE AC DIAGNOSTIC ERROR CODES
Gree Vireo Mini Split Air Conditioner Error Code F0
Refrigerant Leakage Protection
1) Refrigerant leak(s).
2) Indoor coil temperature sensor not calibrated.
3) Refrigerant flow is restricted (ex. valve, exv, debris)
Outdoor Unit Red Light Indicator - 9 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code E1
System High Pressure
1) Over charged with refrigerant.
2) Blocked or dirty outdoor coil.
3) Extreme outdoor ambient conditions
Gree Vireo Mini Split Air Conditioner Error Code E2
Indoor Anti-Freeze Protection
1) Low return airflow.
2) Indoor fan speed is too low.
3) Indoor coil is blocked or dirty.
Outdoor Unit Yellow Light Indicator - 3 flashes and 1 sec Off

Gree Vireo Mini Split Air Conditioner Error Code E4
Compressor High Discharge Temperature Protection
Please refer to the malfunction analysis (discharge temperature, overload) in service manual.
Outdoor Unit Yellow Light Indicator - 7 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code E5
Overcurrent Protection
1) Supply voltage is unstable.
2) Supply voltage is too low and system load is too high.
3) Indoor coil is blocked or dirty.
Outdoor Unit Yellow Light Indicator - 5 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code E6
Communication Malfunction
1) Communication cable is wired incorrectly between indoor and outdoor units.
2) Indoor or Outdoor control board malfunction.
Outdoor Unit Yellow Light Indicator - Continuous On
Gree Vireo Mini Split Air Conditioner Error Code E8
High Temperature Resistant Protection
1) Incorrect refrigerant charge level.
2) Refrigerant metering device malfunction.
3) Compressor malfunction.
Outdoor Unit Yellow Light Indicator - 6 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code EE
EEPROM Memory Malfunction
Control board malfunction.
Outdoor Unit Yellow Light Indicator - 11 flashes and 1 sec Off
Gree Vireo Mini Split Air Conditioner Error Code C5
System Configuration Malfunction
1) No jumper cap inserted on the control board.
2) Incorrect or damaged jumper cap on control board.
3) Indoor and outdoor units are not compatible.
Gree Vireo Mini Split Air Conditioner Error Code Fo
Pump Down or Gathering Refrigerant Status
Optional Service Mode
Outdoor Unit Yellow Light Indicator - 17 flashes and 1 sec Off

NOTE: All of the Gree Air Conditioner Model Numbers below are applicable for the error codes on this page...
Gree AC Vireo Models: VIR09HP115V1A, VIR12HP115V1A, VIR09HP230V1A, VIR12HP230V1A, VIR18HP230V1A, VIR24HP230V1A, VIR30HP230V1A, and VIR36HP230V1A.
Gree Mini Split Air Conditioner Error Code Charts
Gree Mini Split AC Remote Control Button Names
Gree Mini Split AC Remote Control Icons Display Screen

Gree Mini Split Air Conditioner Air Filter Cleaning Procedure
Gree Viero AC Mini Split PDF Owners and Troubleshooting Manual
GREE DUCTLESS AIR CONDITIONING & HEATING SYSTEM INSTALLATION MANUAL
Need help with error codes on your Gree AC? Please leave a question below and we will be happy to help.

CH 5 on these units indicates a communications error between the indoor and outdoor units. Generally, it will require a replacement outdoor board assembly to repair it. Lookup LG parts on the internet or ring them for your nearest Agent or parts. 800 243-0000

5 Flash======
Communication Error (Indoor ? Outdoor)........
Data Communication Fault,,,,,,,

Split = Outdoor unit fan problem. Check Outdoor fan motor is plugged in, Electrically & Mechanically sound, if not replace motor, otherwise replace PCB.
Multi V= Indoor unit EEPROM error - Replace the indoor unit PCB, and then make sure to do Auto addressing and input the address of central control.

This error is a communication error between your indoor and outdoor unit. You can try turning the breaker off for a few minutes and restart the unit. However if that does not work its best suggested to have an authorized HVAC technician service the unit.

ch5 error code, means that there is a
communication error (serial comunication) between the outdoor and the indoor unit.
Only for LG-airconditioners.