and BAE series

or an outdoor fan motor that hums but refuses to spin

as using an incorrect replacement regulator spring can lead to pressure hunting or lock-up issues

Look for visible cracking

moisture-resistant round metal canister

Lennox 42J03 Limit Switch and BAE seriesThe Lennox 42J03 Limit Switch is a critical safety component designed for precise thermal regulation within residential and commercial HVAC systems. This genuine OEM replacement part, also identified as part number 42J0301, features a fixed temperature range of 150 190F with an automatic reset function. As a veteran grade furnace high limit switch, it monitors the plenum temperature and breaks the electrical circuit to the gas valve if overheating is