The 3P 75A contactor architecture ensures that all three legs of power are managed simultaneously

Applications involving ammonia require specific stainless steel or ammonia-compatible pressure control models

While primarily designed for Carrier

Verify the 120V input voltage is stable and check the secondary electrodes for proper gap settings and carbon fouling before replacing the transformer

and system regulation applications

Lennox 81W03 Control Board Els PW 17895 The 3P 75A contactor architectureThe Lennox 81W03 Control Board is the direct OEM replacement for the Lennox 17W70, 17W7001, and 81W0301 ignition control boards. As the central logic for your furnace, this integrated furnace control manages critical sequences, including hot surface ignition, flame sensing, and blower motor timing. It is engineered specifically for use in high efficiency units such as the Lennox G40, G43, and ML180 ML193 series. When performing a field replacement,