Carrier 38YSA - Manual (Page 7)

Fig. 12—Typical Circuit Connections
WIRING DIAGRAM NOTES FOR DUAL FUEL THERMOSTAT:
1. Underlined letters on dual terminal indicates its usage.
For Example: O/W2 means O
O/W2 means W2
Outdoor Temperature Sensor must be attached in all dual fuel installations.
Jumper wire between O/W2 and L thermostat terminals MUST be present.
2. Y1 and O connections to 2-stage furnaces MAY NOT EXIST, or may only be a wire rather than a screw terminal.
A95215
Y/Y2
W/W1
R 24 VAC HOT
FAN
FURNACE
COMPRESSOR
RVS COOLING
N/A
DUAL FUEL
THERMOSTAT
SINGLE-SPEED
HEAT PUMP
24 VAC COM
RVS HEATING
RVS SENSING
OUTDOOR
SENSOR
CONNECTION
G
R R
W
Y Y
G
C C
O/W2
Y1/W2
SINGLE-STAGE
FURNACE
W2
O
OUTDOOR
TEMPERATURE
SENSOR
SEE NOTE 1
S2
S1
L
B
C
Y/Y2
W/W1
R 24 VAC HOT
FAN
FURNACE LO
COMPRESSOR
RVS COOLING
FURNACE HI
DUAL FUEL
THERMOSTAT
SINGLE-SPEED
HEAT PUMP
24 VAC COM
RVS HEATING
RVS SENSING
OUTDOOR
SENSOR
CONNECTION
S2
S1
L
B
G
R R
Y
G
C C C
O/W2
Y1/W2
TWO-STAGE OR
VARIABLE SPEED
FURNACE
W2
O
SEE NOTES 1 AND 2
W/W1
Y/Y2
O
W2
Y1
OUTDOOR
TEMPERATURE
SENSOR
A95216
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