Smart Equipment™ Unit Control Board - York Sun Select YV28 Manual

Smart Equipment™ unit control board
Figure 72: Unit control board
The following tables describe the details of the UCB, see the previous figure for the connection locations.
Table 80: Smart Equipment™ UCB - thermostat connection strip
Location Label
W1 1st stage heating request, 24 VAC input switched from R
W2 2nd stage heating request, 24 VAC input switched from R
Y1 1st stage cooling request, 24 VAC input switched from R
Y2 2nd stage cooling request, 24 VAC input switched from R
G Continuous indoor blower request, 24 VAC input switched from R
OCC Occupancy request, 24 VAC input switched from R
A
X Hard lockout indicator, 24 volt output to a light thermostat LED
R 24 VAC hot for thermostat switching and power
If field-added external accessories for unit shutdown are used, 24 VAC hot
SD-24 out for smoke detector, condensate overflow and/or user shutdown relay
switching in series
C 24 VAC common for thermostat power
96 Installation Manual: YORK
Description
Sun™ Select YV28 to YV50
®
Johnson Controls Ducted Systems
Function and comments
Not effective for cooling-only units
Not effective for cooling-only units or units with single-stage heat sections
Visible in the display menu when the #ClgStgs parameter is set for 2 or more,
also effective for economizer free cooling supply air temperature reset when the
#ClgStgs parameter is set for 1 or more
Must have the OccMode parameter set for External to be effective
If field-added external accessories for unit shutdown are used, 24 VAC hot
return from smoke detector, condensate overflow and/or user shutdown relay
switching in series
Unit wiring harness jumper plug for factory shutdown accessories must be
removed if the switching of field-added external accessories for unit shutdown
are wired between thermostat connection strip SD-24 and R