Fault Code Lookup

HVAC Sales Master
Liquid line transducer validation formula
Field validation formula for liquid-pressure transducer: PSIG = 812.5 × (VDC out / VDC in) - 51.85
This code typically points to
  • Used when validating suspected liquid/high-side transducer error

Next checks to confirm
  1. Measure VDC in at red/black wires at back of transducer harness
  2. Measure VDC out at green/black wires at back of transducer harness
  3. Calculate: PSIG = 812.5 × (VDC out / VDC in) - 51.85
  4. Compare calculated PSIG to actual refrigerant gauge reading

Escalation
None; field diagnostic aid
Reset behavior
Not applicable.
Informational
No action needed
Source
Rheem RP18AZ Installation Instructions sensor-checking section