This Johnson Controls thermostat is built for reliability

Set your multimeter to DC microamps (µA)

and start terminals

It is the direct official replacement for the discontinued Aaon OE392-10

A technician can verify the switch using a multimeter to check for continuity across the terminals when the system is cool

Aprilaire 4740 Relay 320734-701 This Johnson Controls thermostat isThe Aprilaire 4740 Relay is a critical replacement component engineered specifically for Aprilaire 700 series humidifiers, including the 700A and 700M models manufactured after 2008. As a genuine AprilAire humidifier part, this fan relay is responsible for powering the circulator fan when the humidistat signals for moisture. Unlike older "Series One" versions that utilized the 4238 control board with an integrated transformer, this modern 24V