Limit switch circuit open. If the limit does not close within 3 minutes, the furnace goes into a 1-hour soft lockout.
Lennox E250 is the SL280DFNV limit circuit open. If the limit stays open 3 minutes, the furnace goes into a 1-hour soft lockout. The row names firing rate, a blockage in the heater, and airflow. It does not name a dirty filter. E291 is the airflow lockout that does name the filter. E200 is the rollout hard lockout.
Likely causes
- Limit circuit open
- Blockage in the heater
- Airflow problem
- Firing rate not correct for the furnace
Safe checks for E250
- Turn the furnace off and make sure return and supply grilles are open and nothing is blocking them
- Techniciancheck firing rate, look for a blockage in the heater, and check airflow. The code resumes after the fault is cleared
Capacitors can hold a charge after the power is off. Safety terms.
When to call a pro
E250 names firing rate and a blockage in the heater, which are not a filter swap by themselves. E291 is the row that names a dirty filter. If E250 returns, or the furnace goes into the 1-hour lockout, call a licensed HVAC technician.
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Parts & tools for this fix
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High limit and rollout switches: guide
In this code: Limit circuit open
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