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PH4G--B: Installation Instruction
LEGEND
HPS – High Pressure Switch
LCS – Loss of Charge Switch
Step 3 – Defrost Control
Defrost Control
The defrost control is used in all R-410A heat pump models. Its features
include selectable defrost intervals of 30, 60, 90 minutes, and standard
defrost speed up capability. This section describes the sequence of
operation and trouble shooting methods for this control.
Defrost Sequence
The defrost control is a time/temperature control that has field selectable
settings of 30, 60, and 90 minutes. These represent the amount of time
that must pass after closure of the defrost thermostat before the defrost
sequence begins.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
HIGH
QC5
07
09
0L0
08
ALO
C9
C4
QIL
Z2
06
04
D5 D3
JW5
R2
QCB
Y
SSTZ-8
Fig. 19 – Interface Fan Board (IFB)
OUTDOOR COIL
HP S
Accurater
®
Metering De vice
Arrow indicates direction of flo w
Fig. 20 – Typical Heat Pump Operation, Heating Mode
LOW
COM
QC4
QC3
KZ
KL
DCR
QCR
C
R13 C8
R11
Q1
D2
QC1
Q3
AL2
RL
G1
01
G2
A7
R9
AB A15
C0
Z1
U1
R4
C3
C7
JWZ
R3 R5 R6
P2
JW3
R W2 Y
C
W3 W3 W2 W2 C
JW4
P1
Y2
Y1
W3
W2
G
C R
DH
Y
TXV in Bypass
Position
LCS
Metering
Position
The defrost thermostat senses coil temperature throughout the heating
cycle. When the coil temperature reaches the defrost thermostat setting,
it will close, which energizes the DFT terminal and begins the defrost
timing sequence. When the DTF has been energized for the selected
time, the defrost cycle begins, and the control shifts the reversing valve
into cooling position, and turns the outdoor fan off. This shifts hot gas
flow into the outdoor coil which melts the frost from the coil. The
defrost cycle is terminated when defrost thermostat opens, or
automatically after 10 minutes.
21
F1
RL4
P4
INDOOR COIL
A09059
C03012
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