Table 9 - 38AUQ 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 Not used
Y1 Cool 1 DI, 24-vac P2-5 TB-Y1
Wl Heat 1 DI, 24-vac P2-7 TB-Wl
R Power 24-vac P3-1 TRAN2
C Common 24-vac, ground P3-3 TRAN2
DFT1 Defrost Switch DI, 24-vac DFT-1 to DFT-1 DFB
Outputs
Point Name Type of I/O Connection Pin Number Unit Connection Note
OF OD Fan DO, 24-vac OF OFR
RVS1 DO, 24-vac P3-7 to P3-5 RVS1 Energize in COOL
COMP 1 DO, 24-vac P3-10 CADM1 -Y
TB-W2 DO, 24-vac E-HEAT HC-1 (TB4-1)
Configuration
Point Name Type of I/O Connection Pin Number Unit Connection Note
Select Jumper 24-vac P1-1
1 Compressor 24-vac P1-2
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 1-3secs: FactoryTest, defrost runs for 12 seconds or less
Jumper for 5-20 secs: Forced Defrost, defrost runs for 30 secs if DFT1 is open
DFB Power: 24-V at Pin P3-1, COM at P3-3 (required in all modes)
MODE
COOL OFF After COOL HEAT-1 HEAT-2 OFF After HEAT-1 DEFROST During HEAT
Inputs
Y1
Wl
DFT
Outputs
OD Fans
Rev Valve
Compressor
Electric Heat
W2
Notes:
Pin
P2-5 24-V O-V
P2-7 O-V O-V
DFT1 -DFT1 OPEN OPEN
Pin
OF 24-V O-V
P3-7 24-V 24-V
P3-10 24-V O-V
E-HEAT O-V O-V
O-V O-V
O-V
24-V
Note 1
24-V
O-V
24-V
O-V
O-V
O-V
24-V
Note 1
24-V
O-V
24-V
O-V Note 2
24-V
o-v
o-v
Note 1
O-V
O-V
O-V
O-V
O-V
O-V
24-V
CLOSED
O-V
24-V
24-V
24-V
0 or 24-V
1. DFT may be OPEN or CLOSED during Heat mode operation, depending on outdoor coil temperature. Defrost mode cannot start until Time window
opens in DFB Defrost mode logic.
2. Call for electric heat may originate at the space thermostat (space demand) or at the DFB during Defrost. Thermostat signal will also be present on
38AUQ's W2 terminal and the DFB's E-HEAT terminal.
ONTROL BOX
COMPONENT ARRANGEMENT
Q
,@
TQ
_Q
,o®
@®
CAD. Q _
IDT'DATAOI
DT''ORT@
__c
DEFROST BOARD
(DFB}
-- --DFTI
3._ --
-- _OFT?
00 , 00:
Fig. 21 - Defrost Control Board (DFB) Location
C11044
25
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