A failed or tripped 1320547 limit switch often forces the blower into a continuous "on" state as a safety measure to dissipate excess heat

this specific 10k or 12k ohm-style immersion probe is utilized for both the inlet and outlet headers to monitor the temperature delta across the heat exchanger

The KH45LD065 replaces multiple older Carrier part numbers

The Robertshaw 41-602 Norton Mini Ignitor is a high-performance 120V hot surface ignitor engineered for precise ignition in modern residential and light commercial gas furnaces

wired in series with the run winding

Johnson Controls VG2231VM292NGGA Valve Assembly 30067439-890 A failed or tripped 1320547The Johnson Controls VG2231VM292NGGA is a heavy duty 4 inch 2 way normally open flanged globe valve designed for precise flow control in demanding hydronic systems. Built with a rugged cast iron body and durable brass trim, this assembly handles high capacity chilled or hot water applications with a 150 Cv rating. The ANSI Class 125 flat faced flange connection ensures a secure fit for industrial piping. Performance is driven by a tandem mount spring