HVACopediaAirQuest · Furnace
13 Limit circuit lockout
What the control is telling you
The limit circuit opened too many times; the control is in lockout.
Applies to: Carrier/ICP-family two-digit status codes — confirm with the code label on the unit
Likely causes
- Dirty filter / restricted airflow
- Closed supply registers
- Blower not running or wrong speed tap
- Undersized ductwork
- Over-firing
Test and repair steps
- Replace or clean the air filter
- Confirm the blower runs and speed taps are correct for heat
- Check temperature rise against the rating plate
- Inspect ductwork and registers for restrictions
- Check manifold gas pressure
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Source: Carrier/ICP status code label — verify per model. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.