York ZT078-102 Installation Manual

Also see for ZT SERIES: Technical guide

6021980-UIM-A-112070 Johnson Controls Ducted SystemsSmart Equipment™ unit control boardFigure 33: Unit control boardThe following tables describe the details of the UCB, see Figure 33 for the connection locations.AB CHJDQPEGFRIKMLONW1W2Y1GY2OCCCSD-24RXSmart Equipment™ UCB - thermostat connection stripLocation Label Description Function and commentsAW1 1st stage heating request, 24 VAC input switched from R Not effective for cooling-only unitsW2 2nd stage heating request, 24 VAC input switched from R Not effective for cooling-only units or units with single-stage heatsectionsY1 1st stage cooling request, 24 VAC input switched from RY2 2nd stage cooling request, 24 VAC input switched from RVisible in the display menu when the #ClgStgs parameter is setfor 2 or more, also effective for economizer free cooling supply airtemperature reset when the #ClgStgs parameter is set for 1 ormoreG Continuous indoor blower request, 24 VAC input switchedfrom ROCC Occupancy request, 24 VAC input switched from R Must have the OccMode parameter set for External to be effectiveX Hard lockout indicator, 24 volt output to a light thermostat LEDR 24 VAC hot for thermostat switching and powerIf field-added external accessories for unit shutdown are used, 24VAC hot return from smoke detector, condensate overflow and/oruser shutdown relay switching in seriesSD-24If field-added external accessories for unit shutdown are used,24 VAC hot out for smoke detector, condensate overflow and/or user shutdown relay switching in seriesUnit wiring harness jumper plug for factory shutdown accessoriesmust be removed if the switching of field-added externalaccessories for unit shutdown are wired between thermostatconnection strip SD-24 and RC 24 VAC common for thermostat power