3 red flashes
Pressure switch open with inducer pressure above setpoint (switch open when it should be closed)
This code typically points to
- Bad switch
- Bad pressure transducer
- Venting issue
Next checks to confirm
- Verify actual inducer pressure
- Compare to transducer/switch behavior
- Inspect venting and drains
Escalation
If transducer reads correct but switch doesn't agree, switch or board input issue.
Reset behavior
Clears when proof establishes.
Urgent
Fix now