76
Table 53 — MBB Connections
DISPLAY NAME POINT DESCRIPTION SENSOR LOCATION TYPE OF I/O
CONNECTION
PIN NUMBER
INPUTS
Input power from TRAN1 control box 24 VAC J1, 1-3
HUM
Indoor fan output feedback (IGC), or
Space humidity switch
gas section
space
switch input J6, 4
FDWN Fire shutdown switch supply/return/space switch input J6, 5-6
G Thermostat G (Fan) space switch input J7, 2
W2 Thermostat W2 (2nd Stage Heat) space switch input J7, 4
W1 Thermostat W1 (1st Stage Heat) space switch input J7, 6
Y2 Thermostat Y2 (2nd Stage Cool) space switch input J7, 8
Y1 Thermostat Y1 (1st Stage Cool) space switch input J7, 10
SPT Space temperature (T55/56) space 10k thermistor J8, 1-2
SPTO or
RAT
Space temperature offset (T56), or
Return air temperature
space
return
10k thermistor J8, 2-3
OAT Outdoor air temperature outdoor coil support 10k thermistor J8, 5-6
SAT Supply air temperature indoor fan housing, or supply duct 10k thermistor J8, 7-8
SCT.A Saturated condenser temperature, circuit A outdoor coil, circuit A 5k thermistor J8, 9-10
SCT.B Saturated condenser temperature, circuit B outdoor coil, circuit B 5k thermistor J8, 11-12
SCT.C Saturated condenser temperature, circuit C outdoor coil, circuit C 5k thermistor J8, 13-14
FAN.S Fan status switch indoor fan section switch input J8, 15-16
SSP.A Suction pressure, circuit A compressor A suction analog input J8, 18-20
SSP.B Suction pressure, circuit B compressor B suction analog input J8, 21-23
SSP.C Suction pressure, circuit C compressor C suction analog input J8, 24-26
FIL.S Filter status switch indoor fan section switch input J9, 2-3
CS.A1 Compressor A1 feedback control box digital input J9, 4-6
CS.B1 or
CS.A2
Compressor B1 feedback, or
Compressor A2 feedback
control box digital input J9, 7-9
CS.C1 or
CS.B1
Compressor C1 feedback, or
Compressor B1 feedback
control box digital input J9, 10-12
OUTPUTS
Output power to ECB 24 VAC J2, 1-2
Output power to Marquee Display 24 VAC J4, 5-6
CRC Cool-Reheat1 control relay J10, 3
CMP.C or
OFC.2
Compressor C1 relay, or
Outdoor fan 2 relay
relay J10, 6
CMP.B Compressor B1 relay relay J10, 9
CMP.A Compressor A1 relay relay J10, 11
CCH or
OFC.3 or
OFC.1
Crankcase heat relay, or
Outdoor fan 3 relay, or
Outdoor fan 1 relay
relay J10, 13
OFC.2 or
RH2.B
Outdoor fan 2 relay, or
Reheat2 valve, circuit B and C
relay J10, 16
OFC.1 or
RH2.A
Outdoor fan 1 relay, or
Reheat2 valve, circuit A
relay J10, 19
IDF Indoor fan relay relay J10, 21
ALRM Alarm relay relay J10, 23
HT.1 Heat stage 1 relay relay J10, 25
HT.2 Heat stage 2 relay relay J10, 27
COMMUNICATION
Local Equipment Network (LEN) communication J5, 1-3
Carrier Comfort Network (CCN) communication J5, 5-7
Network device power 24 VAC J5, 9-10
CEPL130346-01
STATUS
LEN
J1
J2
J4
J3
J5
J6
J7
J8
J9
J10
CCN
RED LED - STATUS GREEN LED -
LEN (LOCAL EQUIPMENT NETWORK)
YELLOW LED -
CCN (CARRIER COMFORT NETWORK)
INSTANCE JUMPER (SET TO 1)
Fig. 22 — Main Base Board (MBB)
a48-7075
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