Carrier 38YXA - Page 8

Fig. 14—Typical 24-v Circuit Connections using Other HP Thermostats with Fan Coils and No Outdoor
Thermostat, 1 Outdoor Thermostat, or 2 Outdoor Thermostats
A97579
24 VAC HOT






R
C
W2
Y
G
R
W3
W2
G
RVS COOLING








E
W2
OTHER BRAND
HP THERMOSTAT

TWO
OUTDOOR
THERMOSTATS

FA, FB, FX
FAN COIL
HEAT 
PUMP


C
O
R
C
O
INDOOR FAN


HEAT STAGE 2


COOL/HEAT
STAGE 1
24 VAC COM
EMERGENCY 
HEAT
Y
E

ODT


ODT

NOTE: Remove wires from crimp nut in indoor fan coil 
 when installing outdoor thermostats.

IMPORTANT: When using outdoor thermostats, W
2
must be
 energized when requesting supplemental heat.



EHR


EHR


EHR

*
*
*
IF AVAILABLE


*
A97577
24 VAC HOT






R
C
W2
Y
G
R
C
RVS COOLING








C
W2
OTHER BRAND
HP THERMOSTAT

FA, FB, FX
FAN COIL
HEAT 
PUMP


G
O
E
W2
E
W3
R
Y
24 VAC COM


HEAT STAGE 2


COOL/HEAT
STAGE 1
INDOOR FAN
EMERGENCY
HEAT
O
*
*
*
IF AVAILABLE


*
A97580
24 VAC HOT






R
C
W2
Y
G
R
DH
C
RVS COOLING








C
W2
OTHER BRAND
HP THERMOSTAT

FV4A
FAN COIL
HEAT 
PUMP


G
Y/Y2
O
Y1
O
E
W1
W2
R
Y
24 VAC COM


HEAT STAGE 2


COOL/HEAT
STAGE 1
INDOOR FAN
EMERGENCY
HEAT
O

J1 JUMPER


J2 JUMPER

A97578
24 VAC HOT






R
C
W2
Y
G
R
W3
W2
E
G
RVS COOLING








E
W2
OTHER BRAND
HP THERMOSTAT

ONE
OUTDOOR
THERMOSTAT

FA, FB, FX
FAN COIL
HEAT 
PUMP


C
O
R
C
O
INDOOR FAN


HEAT STAGE 2


COOL/HEAT
STAGE 1
24 VAC COM
EMERGENCY
HEAT
Y

ODT

NOTE: Remove wires from crimp nut in indoor fan coil 
 when installing outdoor thermostat.

IMPORTANT: When using outdoor thermostat, W
2
must be
 energized when requesting supplemental heat.


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