LIMIT OPEN (DISPLAY)
Gibson
Open High Limit or Auxiliary Limit Switch
Furnace display or diagnostic label indicates limit open, blower runs but burners off
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Overheating due to restricted airflow, Failed auxiliary rollout or limit switch, Loose wiring to limit circuit, Oversized filter or high static pressure in Gibson duct system
How to Fix / Troubleshooting
Safety first: Turn off power before accessing limit switches. Do not bypass any safety switches.
Steps to check:
- Airflow issues: Replace the air filter with the correct size and MERV rating. Open all registers and ensure returns are not blocked.
- Inspect limit switches: Locate the main high limit on the heat exchanger panel and any auxiliary limits or rollout switches near the burners. Check for loose wires or signs of overheating (discoloration).
- Manual reset rollout: Some rollout switches have a small reset button. If tripped, press gently to reset. If it trips again, stop using the furnace and call a technician to inspect for flame rollout or blocked heat exchanger.
- Professional evaluation: Persistent limit issues require checking static pressure, blower speed settings, and heat exchanger condition.
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Repair Difficulty
Hard
4/5
Required Part
Rollout Switch
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