Pioneer YN020GMFI22M2D Service Manual page 37

8.4.1.3 Zero-crossing signal detection error diagnosis and solution.
Malfunction decision
conditions
Supposed causes
Trouble shooting:
Check if the connections and
power supply is normal ?
Yes
Indoor main PCB is
defective. Replace indoor
main PCB.
When PCB does not receive zero crossing signal feedback for
4 minutes or the zero crossing signal time interval is abnormal.
● Connection mistake
● PCB faulty
Correct the connections . Turn on the
No
unit when the power supply is good .
PIC3: Main board LED when power on and
unit standby.
PIC 4: Check point button, press 1 time for check
how many indoor units are connected.