The Lennox 57M66 Pressure Switch is a critical safety component designed for precise combustion air proving in high-efficiency gas furnaces

Precision Draft Calibration: Field-adjustable from

Designed for direct installation after the compressor

Cracked or warped transitions can lead to pressure switch trip errors

Carrier HT01BD702 Transformer 318423-701 The Lennox 57M66 Pressure SwitchThe Carrier HT01BD702 transformer is a critical factory authorized replacement designed to provide reliable voltage conversion for commercial HVAC systems and rooftop units. Engineered to handle a 460V primary input, this step down transformer delivers a consistent 24V secondary output, powering essential low voltage components such as thermostats, contactor coils, and integrated circuit boards. With a 75VA power rating, it offers sufficient capacity