York ZT SERIES - Smart Equipment Unit Control Board; Unit Control Board

6021980-UIM-A-1120
70 Johnson Controls Ducted Systems
Smart Equipment™ unit control board
Figure 33: Unit control board
The following tables describe the details of the UCB, see Figure 33 for the connection locations.
A
B
C
HJ
D
Q
P
E
G
F
R
IK
M
L
O
N
W1
W2
Y1
G
Y2
OCC
C
SD-24
R
X
Smart Equipment™ UCB - thermostat connection strip
Location Label Description Function and comments
A
W1
1st stage heating request, 24 VAC input switched from R Not effective for cooling-only units
W2
2nd stage heating request, 24 VAC input switched from R
Not effective for cooling-only units or units with single-stage heat
sections
Y1
1st stage cooling request, 24 VAC input switched from R
Y2
2nd stage cooling request, 24 VAC input switched from R
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
G
Continuous indoor blower request, 24 VAC input switched
from R
OCC
Occupancy request, 24 VAC input switched from R Must have the OccMode parameter set for External to be effective
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 return from smoke detector, condensate overflow and/or
user shutdown relay switching in series
SD-24
If 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 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
C
24 VAC common for thermostat power