American Standard *UD Series Operation Manual page 67

Legend – System Wiring
50A52 Model
Terminal
Number Type
W
G
R captive screw
Y or
3/16" spade
C
HLO
ROI
PC
PCOM
PO 12-pin
FSI connector
FSO and
GE harness
GR
GM
GC
FSMV
PARK
(2 terminals)
HEAT
COOL
LINE
XFMR
IND 1/4" spade
IGN
LINE (neutral)
CIRC (neutral)
IND (neutral)
IGN (neutral)
XFMR
TR 3/16" spade
TH
System Component Connection
low voltage thermostat W terminal (or equivalent)
low voltage thermostat G terminal (or equivalent)
low voltage thermostat R terminal (or equivalent)
low voltage thermostat Y terminal (or equivalent) or
2nd wire from Y terminal goes to 24 VAC HOT side of
compressor contactor coil
24-VAC COMMON side of compressor contactor coil
high limit OUTPUT
rollout INPUT
pressure switch CLOSED contacts
pressure switch COMMON
pressure switch OPEN contacts
flame switch INPUT
flame switch OUTPUT
gas valve – EQSO
gas valve – REDUNDANT
gas valve – MAIN
gas valve – COMMON
flame switch main valve
unused circulator blower terminals
circulator blower HEAT SPEED terminal
circulator blower COOL SPEED terminal
input voltage (120 VAC) HOT SIDE
24 VAC transfomer line voltage HOT SIDE
inducer HOT side
ignitor HOT side
line NEUTRAL side
circulator blower NEUTRAL side
inducer NEUTRAL side
ignitor NEUTRAL side
transformer NEUTRAL side
24 VAC transformer (low voltage COMMON side)
24 VAC transformer (low voltage HOT side)
66