larger rooftop units (RTUs)

This specific model (64160) is the standard B1H-30

it features an integrated SPDT auxiliary switch for position signaling or interlocking safety circuits

A failed sequencing relay often prevents power from reaching the heating elements even if the motor circuit is engaged

Lennox 10M65 Limit Switch 318518-761 larger rooftop units (RTUs)The Lennox 10M65 Limit Switch is a critical safety component designed for precise thermal regulation within residential gas furnaces and air handlers. Engineered as a 135 175F AUTO limit switch, this Lennox 10M65 functions as a primary high limit control, essential for preventing heat exchanger overheating. When internal temperatures exceed the 175F threshold, the internal bimetal disc opens the circuit to terminate the heating cycle. Once the system