Lennox 57M66 Furnace Pressure Switch

The Lennox 57M66 is a genuine OEM pressure switch designed specifically for Lennox residential gas furnaces. This safety component monitors air pressure within the furnace system to ensure proper venting and combustion air flow before allowing the furnace to ignite.

Key Features:

• Genuine Lennox OEM replacement part (part number 57M66)
• Pressure-activated safety switch for furnace operation
• Monitors inducer motor and venting system performance
• Prevents furnace ignition when improper pressure is detected
• Direct replacement for failed or malfunctioning pressure switches

Pressure switches are critical safety devices that verify proper draft pressure before the gas valve opens. When the inducer motor creates adequate negative pressure, the switch closes to signal the control board that it's safe to proceed with ignition. A faulty pressure switch can prevent the furnace from starting or cause intermittent operation. This genuine Lennox replacement ensures reliable performance and proper integration with your furnace's control system.

Common Symptoms of Failure: Furnace won't ignite, igniter glows but no flame, fault codes related to pressure switch failure, or intermittent furnace operation.