St9120c Furnace Control Board Wiring Diagram. 1 marked ol if alarm contact is supplied. This control is the central wiring point for most of the electrical components in the furnacethe basic purposes of the st9120 are to monitor the thermostat for heat cool and fan demands run the induced draft blower motor and run a circulating fan up to two speeds as required.
Fan motor wires a. So yes it will work in an armstrong furnace. Wiring diagrams are made up of two points.
I am replacing a furnace board st9120c 4057 with the new one st9120u.
A wiring diagram is a kind of schematic which uses abstract pictorial signs to reveal all the affiliations of parts in a system. The control board is the brain of your unit coordinating and executing the operation of other various components by sending voltage when and where needed. The wiring diagram provided by honeywell does not address on which terminals the orange wires labeled 22 and 21 these leads went to the motor lead terminals on the original controller. Gas furnace control board wiring diagram just whats wiring diagram.