Lennox 49M50 Pressure Switch L99H008 The Johnson Controls P74AA-1 is

The Johnson Controls P74AA-1 is a robust differential pressure control designed primarily for monitoring lube oil pressure in high-performance refrigeration compressors

This unit is an HST (High Starting Torque) model

Product Specifications

While designed for a straightforward replacement

Lennox 49M50 Pressure Switch L99H008 The Johnson Controls P74AA-1 isThe Lennox 49M50 is a high performance HVAC high pressure switch designed for critical system monitoring in residential and commercial cooling applications. This genuine OEM Lennox pressure switch functions as a primary safety control, specifically calibrated for a 640 psig cut out (C O) threshold. When refrigerant pressures exceed this safety limit, the switch breaks the electrical circuit to the compressor, preventing catastrophic component failure