HVACopedia

AirQuest · Furnace

33 Limit circuit fault

High severity

What the control is telling you

Main limit, rollout or auxiliary limit is open.

Applies to: Carrier/ICP-family two-digit status codes — confirm with the code label on the unit

Likely causes

  • Restricted airflow
  • Flame rollout
  • Faulty limit switch
  • Blower issue

Test and repair steps

  1. Check filter, blower and duct restrictions
  2. Check rollout switches — if tripped, inspect heat exchanger and venting before resetting
  3. Verify temperature rise
  4. Test limit switches for continuity when cool

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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.