Honeywell TH9421C1004 Thermostat Manual PDF

Download the official Honeywell TH9421C1004 VisionPRO IAQ Thermostat manual PDF for complete installation and configuration instructions. This manual explains how to mount the touch-screen thermostat, connect wiring to the equipment interface module, configure heating and cooling stages, set schedules, adjust fan and ventilation settings, and run system tests. It also includes installer setup functions, wiring diagrams, error codes, and safety guidelines to ensure proper operation of the Honeywell VisionPRO IAQ programmable thermostat.