hvac - How to diagnose a broken Aprilaire humidifier (Model 600)? - Home Improvement Stack Exchange

I have an Aprilaire Humidifier Model 600 (or maybe 600M) mounted on my furnace. The humidifier is not turning on (i.e. letting water flow over the filter) when the furnace is on. The below images

wiring - Aprilaire 600 to Fedders furnace - Home Improvement Stack

Aprilaire 600 - maybe incorrectly installed?

Aprilaire 600 Humidifier - Not Working? : r/hvacadvice

Aprilaire 600 Humidifier Parts Repair Help

hvac - How to troubleshoot a leak in an Aprilaire humidifier

BUY WITH CONFIDENCE This humidifier was designed and manufactured in the USA by AprilAire – the inventor of the whole home evaporative humidifier, and

AprilAire 600 Whole-House Humidifier, Automatic High Output Furnace Humidifier, Large Capacity Whole-House Humidifier for Homes up to 5,000 Sq. Ft.

wiring - Aprilaire 600 to Fedders furnace - Home Improvement Stack

Aprilaire 600 Humidifier Parts Repair Help

BUY WITH CONFIDENCE This humidifier was designed and manufactured in the USA by Aprilaire – the inventor of the whole home evaporative humidifier, and

Aprilaire 600M Whole Home Humidifier with Manual Control + Bypass Humidifier Installation Kit, High Output Furnace Humidifier, Large Capacity Whole