Fault Code Lookup

HVAC Sales Master
2 red flashes
Pressure switch closed with inducer pressure below setpoint (switch closed when it should be open)
This code typically points to
  • Bad pressure switch
  • Bad pressure transducer
  • Misread proofing state

Next checks to confirm
  1. Verify transducer/switch agreement
  2. Check startup condition
  3. Compare transducer reading to switch behavior

Escalation
Transducer/switch disagreement indicates sensor or board issue.
Reset behavior
Clears when startup proofing is normal.
Urgent
Fix now
Source
YP9C install manual