While factory-set to 3

it requires a minimum differential pressure of approximately 0

5" length and your specific model's part number before installation

For fail-safe operation

Lennox 38M78 Ambient Switch 324846-701 While factory-set to 3This Lennox 38M78 Ambient Switch is a critical pressure actuated component designed for head pressure control in low ambient cooling applications. Engineered for precision, this low ambient pressure switch ensures reliable operation of your HVACR system when outdoor temperatures drop, preventing compressor slugging and maintaining the necessary pressure differential for efficient thermal transfer. The Lennox 38M7801 features a specific cut in point of