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Inputs
Point Name
G Fan
Y1 Cool 1
Y2 Cool 2
W1 Heat 1
W2 Heat 2
R Power
C Common
DFT1
DFT 2
Outputs
Point Name
IFO Fan On
OF OD Fan On
RVS1
RVS2
COMP 1
COMP 2
HEAT 2
COM
Configuration
Point Name
Select Jumper
2 Compressor
Speed−Up Configuration
Point Name
Speed-Up Jumper
Speed-Up Jumper
Jumper for 1−3 seconds: Factory Test, defrost runs for 9 seconds
Jumper for 5−20 seconds: Forced Defrost, defrost runs for 30 seconds if DFT2 is open
Reversing valve control — The DFB has two outputs for
unit reversing valve control. Operation of the reversing
valves is based on internal logic; this application does not
use an "O" or "B" signal to determine reversing valve
position. Reversing valves are energized during the
cooling stages and the defrost cycle and de−energized
during heating cycles. Once energized at the start of a
cooling stage, the reversing valve will remain energized
until the next heating cycle demand is received. Once
de−energized at the start of a Heating cycle, the reversing
Fig. 34 − Defrost Control Board Location
Table 8 – 50TCQ Defrost Board I/O and Jumper Configurations
Type of I/O
Connection Pin Number
DI, 24Vac
P2-3
DI, 24Vac
P2-5
DI, 24Vac
P2-4
DI, 24Vac
P2-7
DI, 24Vac
P2-6
24Vac
P3-1
24Vac
P3-2
DI, 24Vac
DFT-1 to DFT-1
DI, 24Vac
DFT-2 to DFT-2
Type of I/O
Connection Pin Number
DO, 24Vac
P3-9
DO, 24Vac
DO, 24Vac
P3-7 to P3-5
DO, 24Vac
P3-6 to P3-4
DO, 24Vac
P3-10
DO, 24Vac
P3-8
DO, 24Vac
E-HEAT
24Vac
P3-3
Type of I/O
Connection Pin Number
24Vac
P1-1
24Vac
P1-3
Type of I/O
Connection Pin Number
JMP17
JMP18
Unit Connection
LCTB-G
LCTB-Y1
LCTB-Y2
LCTB-W1
LCTB-W2
CONTL BRD-8
CONTL BRD-4
Unit Connection
REHEAT-2
OF
OFR
FPT - REHEAT-6
REHEAT-8
HC-1 (TB4-1)
HC-1 (TB4-3)
Unit Connection
Unit Connection
valves will remain de−energized until the next cooling
stage is initiated.
Compressor control — The DFB receives inputs
indicating Stage 1 Cooling, Stage 2 Cooling (sizes 08 −
14) and Stage 1 Heating from the space thermostat or unit
control
system (PremierLink® or RTU−OPEN); it
generates commands to start compressors with or without
reversing valve operation to produce Stage 1 Cooling (one
compressor), Stage 2 Cooling (both compressors run) or
26
C09276
Note
Note
Energize in COOL
Energize in COOL
Note
Use for 50TCQD
Note
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