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Discussion Starter · #1 ·
I have a Heil furnace that is flashing a diagnostic code = Low Pressure Switch Stuck Open or Aux. Limit Switch Open. When the thermostat is set above the room temp, the furnace starts, but the burner does not light.

Is this something easy to fix? I'm not familiar with furnaces, but I am relatively handy.

Also, the thermostat flashed low battery, but then went completely off. The batteries were replaced, but I thought the battery was just for backup. After the batteries were replaced, the furnace worked, but then it stopped and flashed the above code. I'm not sure if this is related to the problem or not.

Thank you.

· Registered
438 Posts
You are going to have to run a complete saftey check of the system to locate the flaw. The board is more or less telling you where to look for the problem, its letting you know that a possible problem exisits in the pressure switch, and or aux limit could have a possible open switch.
I would first test each switch for any possible problem, starting with the pressure switch, and moving through the diagram all of the other switches.

Good Luck
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