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NOTE: If the TEST pins are jumpered and the 5-minute delay is
being bypassed, the LO PS terminal signal is not ignored during
the 90-second start-up period.
Defrost Control Board Diagnostic LEDs
Mode
No Power to Board
Normal Operation/Power to Board
Short Cycle Lockout
Low Pressure Switch Fault
Low Pressure Switch Lockout
High Pressure Switch Fault
High Pressure Switch Lockout
NOTES:
Because the pressure switches are monitored only when "Y1"
(Input) is active, the code for pressure switch open will not be
seen when "Y1" is off. Instead, the "Normal Operation" or
"Short Cycle Lockout" code will be seen.
When a pressure switch opens and causes a short cycle
lockout, the pressure switch-open code will be seen until it
closes, then the short cycle lockout code will flash unless it
has already expired.
Adjust Defrost System
Defrost Control Board
Optional high pressure switch connections
NOTE: To add the pressure switch, remove the factory-installed
jumper.
P1
30
A
60
90
TEST
B
P5
C
D
O-OUT
LO-PS
E
DF
F
Y1-OUT
K3 Relay
HI-PS
G
A. Defrost time setting pins
B. Test pins
C. Compressor delay pins
D. Reversing valve
E. Low pressure switch (optional)
Green LED
Red LED
(DS2)
(DS1)
Off
Off
Simultaneous Slow Flash
Alternating Slow Flash
Off
Slow Flash
Off
On
Slow Flash
Off
On
Off
FAN
C2
K1 Relay
DS1
H
DS2
U2
K2 Relay
U1
P2
W1
L
C
24V
L
I
R
C5
O
Y1
P6
TST PS DF C
R O Y1
F. Defrost thermostat
G. High pressure switch (optional)
H. Diagnostic LEDs
I. Low voltage terminal strip
connections
Adjust Time Between Defrost Cycles
WARNING
Electrical Shock Hazard
Disconnect power before servicing.
Replace all parts and panels before operating.
Failure to do so can result in death or electrical shock.
1. Disconnect power.
2. Remove the heater compartment access panel.
3. Adjust the time period between defrost cycles by placing the
defrost time plug in the proper position. See "Defrost Control
Board."
For 30-minute intervals between defrost cycles, connect
the Defrost Time Setting Plug to the pins corresponding
to 30.
For 60-minute intervals between defrost cycles, connect
the Defrost Time Setting Plug to the pins corresponding
to 60 (this setting is the factory preset setting).
For 90-minute intervals between defrost cycles, connect
the Defrost Time Setting Plug to the pins corresponding
to 90.
4. Replace the heater compartment access panel.
5. Reconnect power.
Troubleshoot the Defrost System
Diagnostic LEDs
The defrost board uses 2 LEDs for diagnostics. The LEDs flash a
specific sequence according to the condition.
Defrost Control Board Diagnostic LED
Mode
No Power to Board
Normal Operation/Power to Board
Short Cycle Lockout
Low Pressure Switch Fault
Low Pressure Switch Lockout
High Pressure Switch Fault
High Pressure Switch Lockout
Green LED
Red LED
(DS2)
(DS1)
Off
Off
Simultaneous Slow Flash
Alternating Slow Flash
Off
Slow Flash
Off
On
Slow Flash
Off
On
Off
9
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