Fault Code Lookup

HVAC Sales Master
T904_O
Inverter Fault - DC Bus Overvoltage
This code typically points to
  • Internal DC voltage too high

Next checks to confirm
  1. Verify supply/internal voltage condition

Escalation
3-strikes to 30-minute lockout
Reset behavior
Auto after 30 minutes if fault clears.
Urgent
Fix now
Source
Rheem RP18AZ Installation Instructions Table 15