HVAC Systems · Furnace Components
High-Limit Switch
A temperature-sensing safety switch in the furnace heat-exchanger compartment that shuts off the burners if the plenum overheats, protecting the heat exchanger from cracking due to restricted airflow.
Common uses
Overheat protection, burner shutoff on airflow loss
Common symptoms
- Furnace short cycles on high temperature
- Burners light then shut off
- No heat after dirty filter
Common repairs
- Restore airflow (filter/blower)
- Switch replacement
- Duct restriction cleanup
Related terms
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