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20
HIGH LOW COM
QC5
QC4
QC3
KZ
KL
07 09 080L0
ALO
R13 C8 R11 Q1
Q3
D2
AL2
DCR QCR
QC1
C
RL
01
G1
G2
Z1
A7 R9 AB A15
C4
C9
C0
QIL Z2 06 04
U1
C3
R4 RL4
JWZ
C7
D5 D3
R3 R5 R6
R2
JW5
QCB
Y
R W2Y C W3W3W2W2C
JW4
P2
JW3
P4
P1
W2W3
Y2 Y1
YDH
GCR
SSTZ-8
P3
SDL
24VAC/R3AMP CDM/C
F1
STD
DEHUM
A09059
Fig. 16 -- Interface Fan Board (IFB)
COMPRESSOR
ACCUMULATOR
OUTDOOR COIL
INDOOR COIL
LCS
LEGEND
HPS – High Pressure Switch
LCS – Loss of Charge Switch
Accurater
®
Metering De vice
Arrow indicates direction of flo w
Position
HP S
TXV in Bypass
Metering
Position
C03012
Fig. 17 -- Typical Heat Pump Operation, Heating Mode
Step 3 — Defrost Control
Quiet Shift
Quiet Shift is a field--selectable defrost mode, which will eliminate
occasional noise that could be heard at the start of defrost cycle and
restarting of heating cycle. It is selected by placing DIP switch 3
(on defrost board) in ON position.
When Quiet Shift switch is placed in ON position, and a defrost is
initiated, the following sequence of operation will occur. Reversing
valve will energize, outdoor fan will turn off, compressor will turn
off for 30 sec and then turn back on to complete defrost. At the
start of heating after conclusion of defrost reversing valve will
de--ener gize, compressor will turn of f for another 30 sec, and the
outdoor fan will stay off for 40 sec, before starting in the Heating
mode.
Defrost
The defrost control is a time/temperature control which includes a
field--selectable time period (DIP switch 1 and 2 on the board)
between defrost cycles of 30, 60, 90, or 120 minutes (factory set at
60 minutes). To initiate a forced defrost, two options are available
depending on the status of the defrost thermostat.
If defrost thermostat is closed, speed-- up pins (J1) must be shorted
by placing a flat head screw driver in between for 5 sec and
releasing, to observe a complete defrost cycle. When the Quiet
Shift switch is selected, compressor will be turned off for two 30
sec intervals during this complete defrost cycle, as explained
previously. When Quiet Shift switch is in factory default OFF
position, a normal and complete defrost cycle will be observed.
If defrost thermostat is in open position, and speedup pins are
shorted (with a flat head screw driver) for 5 sec and released, a
short defrost cycle will be observed (actual length is dependent
upon the selected Quiet Shift position). When Quiet Shift switch is
in ON position, the length of defrost is 1 minute (30 sec
compressor of f period followed by 30 sec of defrost with
compressor operation). On return to heating operation, compressor
will again turn off for an additional 30 sec and the outdoor fan for
40 sec. When the Quiet Shift is in OFF position, only a brief 30
sec. cycle will be observed.
NOTE: Unit will remain in defrost until defrost thermostat
reopens at approximately 65_F(18_C) coil temperature at liquid
line or remainder of defrost cycle time.
50VT--A