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Fig. 23 — Defrost Control Board (DFB) Arrangement
POINT NAME
INPUTS
G Fan
Y1 Cool 1
W1 Heat 1
R Power
C Common
DFT1 Defrost Switch
DFT2 Defrost Switch
OUTPUTS
OF OD Fan
RVS1
RVS2
COMP 1
TB-W2
CONFIGURATION
Select Jumper
1 Compressor
SPEED-UP CONFIGURATION
Speed-Up Jumper
Speed-Up Jumper
NOTE(S):
a
Jumper for 1-3 secs: Factory Test, defrost runs for 12 seconds or less. Jumper for 5-20 secs: Forced Defrost, defrost runs for 30 secs if DFT2 is open.
26
DIP
Switches
Speed-Up
Jumpers
Table 12 — CHS Defrost Board I/O and Jumper Configurations
TYPE OF I/O
CONNECTION PIN NO.
DI, 24-vac
DI, 24-vac
DI, 24-vac
24-vac
24-vac, ground
DI, 24-vac
DI, 24-vac
DO, 24-vac
DO, 24-vac
DO, 24-vac
DO, 24-vac
DO, 24-vac
24-vac
24-vac
Fig. 24 — Defrost Control Board (DFB) Location
Specifications subject to change without notice.
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 deter-
mine reversing valve position. Reversing valves are ener-
gized 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 re-
main de-energized until the next Cooling stage is initiated.
COMPRESSOR CONTROL
The DFB receives inputs indicating Stage 1 Cooling and
Stage 1 Heating from the space thermostat or third-party
Building Management System; it generates commands to
start compressors with or without reversing valve operation
to produce Stage 1 Cooling (one compressor), or Stage 1
Heating (both compressors run).
UNIT CONNECTION
P2-3
P2-5
P2-7
P3-1
P3-3
DFT-1 to DFT-1
DFT-2 to DFT-2
OF
P3-7 to P3-5
P3-6 to P3-4
P3-10
E-HEAT
P1-1
P1-2
JMP17
JMP18
a
Not used
TB-Y1
TB-W1
TRAN2
TRAN2
DFB
DFB
OFR
RVS1
Energize in COOL
RVS2
Energize in COOL
CADM1-Y
HR
CHS-180-240-01SI Rev. A
NOTE
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