Fault Code Lookup

HVAC Sales Master
T957_O
Low Refrigerant Pressure (transient)
This code typically points to
  • Low-charge / airflow / EXV / restriction family

Next checks to confirm
  1. Same low-suction-pressure evaluation path as 21L/A957_O

Escalation
3-strikes to 4-hour lockout
Reset behavior
Auto after 4 hours if cleared.
Urgent
Fix now
Source
Rheem RP18AZ Installation Instructions Table 15