Lennox 38M77 Pressure Switch 318973-401 If you are troubleshooting an

If you are troubleshooting an oil burner that won't fire

Sourcing a reliable OEM 2 HP condenser fan motor is critical for maintaining the high-performance cooling required in large-scale commercial HVAC systems

This board is a confirmed fit for the FK4BNF003000AAAA air handler series

though common mechanical failure of the internal diaphragm also necessitates a replacement switch

Standard replacement motors typically require a new run capacitor (check the nameplate for MFD rating) to ensure proper starting torque and motor longevity

Lennox 38M77 Pressure Switch 318973-401 If you are troubleshooting anThe Lennox 38M77 High Pressure Switch is a critical OEM safety component designed for R 410A HVAC systems. Engineered to monitor discharge line pressure, this switch prevents compressor damage by interrupting the control circuit when pressures exceed safe operating limits. With a factory calibrated trip setting of 640 psi and a reset threshold of 475 psi, it ensures precise high limit protection in commercial and industrial rooftop units and split