13.1
Limit circuit lockout
This code typically points to
- Limit or flame rollout switch open longer than 3 minutes
- Low airflow, blocked filter/coil, blower-speed mismatch, rollout-related combustion problem
Next checks to confirm
- Identify whether the open device is main limit, draft safeguard, rollout, or blocked-vent branch
- Verify airflow/static/blower first if it is a limit event
Escalation
Manual-reset rollout or repeated limit cycling after airflow correction indicates higher-risk combustion or HX issue.
Reset behavior
Auto-resets after 3 hours.
Safety Critical
Immediate concern