Panasonic WH-ADF0309J3E5CM Service Manual page 241

24.2.3 E04 - Error in Indoor Unit Receiving Signal from Outdoor Unit
Wiring/Power Supply issue:

No communication from outdoor unit within 3 minutes or no signal from outdoor unit
Outdoor Unit main power supply turned OFF.
o
No proper set for indoor unit resistance impedance terminal (CN045)
o
Communication cable is lose/opened/improper install.
o
Setting Related:

CHK and TEST pin shorted.

EEPROM no installed or defect when main power switched ON.

Outdoor unit main PCB malfunction.

Wrongly set the indoor unit address (duplicated)
EEPROM
DISP Pin CHK Pin
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