3 flashes w/pause
Outdoor thermistor failure
This code typically points to
- Failed outdoor-air thermistor
- Open/shorted sensor
- Wiring damage
Next checks to confirm
- Inspect sensor resistance and harness
- Verify sensor placement
Escalation
If sensor values are correct at the board, control-board input fault becomes more likely.
Reset behavior
No public reset timing documented in install/start-up manual.
Service Soon
Schedule repair