The Rheem-Ruud 42-21268-04 Door Switch is a critical safety component designed for precise interlock control in residential and commercial furnaces and air handlers

For standard steam applications

making it suitable for standard hot water heating and chilled water cooling cycles

A key advantage for service technicians is the removable motor assembly

this 1-gallon (3

Trane CNT7679 Control Board 322056-301 The Rheem-Ruud 42-21268-04 Door SwitchThe Trane CNT7679 Control Board is a critical OEM 120v HSI 1 stage replacement engineered for high performance gas furnaces. Designed to manage the ignition sequence and blower timing, this integrated furnace control board provides precise regulation for hot surface ignition systems. As a veteran spec part, the CNT7679 replaces a wide range of legacy components including CNT7979, CNT3799, and CNT2183, ensuring backward compatibility with furnaces