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29
Table 9 — Thermistors
WIRING DIAGRAM
DESIGNATION
THERMISTOR
FIELD
CONNECTION
CONTROLLER
CONNECTION
REFERENCE
VOLTAGE
COMMENTS
DTT
Discharge
Temperature
Thermistor
Factory
AUX-J6 CH11
5.0 vdc
Digital compressor units only
OAT
Outside Air
Temperature
Factory
MBB-J8-7, 8
4.0 vdc
RAT
Return Air
Temperature
LVT-19, -20
MBB-J8-11, 12
4.0 vdc
RGTA
Return Gas
Thermistor, Circuit A
Factory
MBB-J8-1, 2
4.0 vdc
Not used on 38APS065
RGTB
Return Gas
Thermistor, Circuit B
Factory
MBB-J8-3, 4
4.0 vdc
38APD and 38APS065 only
SAT
Supply Air
Temperature
LVT-11, -19
MBB-J8-12, 13
4.0 vdc
T55
Space Temperature
Thermistor
LVT-21, -22
MBB-J8-9, -6
4.0 vdc
T56
Space Temperature
Thermistor
LVT-21, -22
MBB-J8-9, -6
4.0 vdc
Space Temperature
Offset
LVT-22, -23
MBB-J8-6, -5
4.0 vdc
DUCT
SUPPLY
SAT
FS2
OR
FS1*
FAN
EVAPORATOR
COIL
MAT/RAT
RETURN
AIR
OUTSIDE
AIR
LEGEND
*FS1 or FS2 can be pressure differential switch (shown), motor current detection, or sail
switch.
FS1
—
Fan Status Switch (24-v)
MAT
—
Mixed Air Temperature Sensor
RAT
—
Return Air Temperature Sensor
SAT
—
Supply Air Temperature Sensor
a38-7133
Fig. 24 — Mixed Air Temperature (MAT)/Return Air Temperature (RAT), Supply Air Temperature (SAT)
and Fan Status Switch Sensor Layout