Lennox MPA012S4S-1L

Lennox Mini-Split Service Manual / Page 220
F4 Fault Code
Basic Description:
Outdoor EEPROM error.
General Note:
PCB main chip does not receive feedback from EEPROM chip. EEPROM: a read-only
memory whose contents can be erased and reprogrammed using a pulsed voltage.
For the location of EEPROM chip, please refer to the below photos.