Carrier 42QHF012DS Service Manual page 59

12.3 Trouble shooting
12.3.1 For the indoor unit
12.3.1.1 Indoor EEPROM malfunction
Shut off the power supply and
turn it on 1 minute later. Is it
still displaying the error code?
Yes
If the EEPROM chip
is welded on PCB,
replace the PCB
directly. Otherwise,
check whether the
EEPROM chip
plugged in PCB well?
Yes
Replace the indoor PCB.
EEPROM: An electrically erasable programmable read-only memory whose contents can be erased and
reprogrammed using a pulsed voltage.
12.3.1.2 Indoor / outdoor units communication error
No
Insert the EEPROM well
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