Fault Code Lookup

HVAC Sales Master
A906_O
Inverter Fault - AC Input Overvoltage
This code typically points to
  • Supply/internal voltage outside acceptable range

Next checks to confirm
  1. Verify line voltage and inverter input conditions

Escalation
Lockout while active, short cycle to restart
Reset behavior
Clears when voltage returns to acceptable range.
Urgent
Fix now
Source
Rheem RP18AZ Installation Instructions Table 15 and over/under-voltage description