K. Sail Switch (Gas Models Only)
The sail switch is located on the front of the burner box. A sail switch consists of a round damper plate on a lever arm which is in contact with an electric switch. When the fan or air blower comes on, it draws air through the gas burner. This creates a negative pressure inside the burner box, and this negative pressure pulls in the round damper and activates the sail switch. If there is improper air flow, the damper will not pull in, preventing the burner from starting. The display will also read "no airflow flow" with an audio indication. Improper airflow can be caused by improperly designed exhaust ducting where the duct run is too long or has too many sharp bends in it. It can also be caused by a lack of makeup air.
L. Hi-Limit (Gas Models Only)
Prior to May 26, 1998. The high limit thermostat is an automatic reset
As of May 26, 1998. The high limit thermostat is a manual reset
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