Bryant 548J - Manual (Page 22)

22
C09276
Fig. 27 -- Defrost Control Board (DFB) Location
Table 9 – 548J Defrost Board I/O and Jumper Configurations
Inputs
Point Name Type of I/O Connection Pin Number Unit Connection Note
G Fan DI, 24---vac P2---3 LCTB---G
Y1 Cool 1 DI, 24---vac P2---5 LCTB---Y1
Y2 Cool 2 DI, 24---vac P2---4 LCTB---Y2
W1 Heat 1 DI, 24---vac P2---7 LCTB---W1
W2 Heat 2 DI, 24---vac P2---6 LCTB---W2
R Power 24---vac P3---1 CONTL BRD---8
C Common 24---vac P3---2 CONTL BRD---4
DFT1 DI, 24---vac DFT---1 to DFT---1
DFT 2 DI, 24---vac DFT---2 to DFT---2
Outputs
Point Name Type of I/O Connection Pin Number Unit Connection Note
IFO Fan On DO, 24---vac P3---9 REHEAT---2
OF OD Fan On DO, 24---vac OF OFR
RVS1 DO, 24---vac P3---7 to P3---5 Energize in COOL
RVS2 DO, 24---vac P3---6 to P3---4 Energize in COOL
COMP 1 DO, 24---vac P3---10 FPT --- REHEAT---6
COMP 2 DO, 24---vac P3---8 REHEAT---8
HEAT 2 DO, 24---vac E---HEAT HC---1 (TB4---1)
COM 24---vac P3---3 HC---1 (TB4---3)
Configuration
Point Name Type of I/O Connection Pin Number Unit Connection Note
Select Jumper 24---vac P1---1
2 Compressor 24---vac P1---3 Use for 548J***D
Speed--Up Configuration
Point Name Type of I/O Connection Pin Number Unit Connection Note
Speed---Up Jumper JMP17
Speed---Up Jumper JMP18
Jumper for 1--3 secs: Factory Test, defrost runs for 9 secs
Jumper for 5--20 secs: Forced Defrost, defrost runs for 30 secs 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 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 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 and
09 only) and Stage 1 Heating from the space thermostat or
unit control system (RTU--MP); 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 Stage 1
Heating (both compressors run).
548J