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REPLACEMENT DEFROST CONTROL BOARD
PRESSURE
SWITCH
SAFETY CIRCUIT
CONNECTIONS
CONNECTION FOR
ONE OPTIONAL SWITCH
PS2
PS1
CONNECTIONS FOR
TWO OPTIONAL
SWITCHES
[] ps2
Psi
SERVICE LIGHT
....... ONNECT,ON
......................... .........................
DIAGNOSTIC LEDs
/
DEFROST INTERVAL
TIMING PINS
24V TERMINAL STRIP
CONNECTIONS
FIGURE 1
Time-Delay
The timed-off delay is five minutes long. The delay
feature is provided to help protect the compressor in
case of an interruption in power to the unit or when a
pressure switch resets.
Pressure Switch Safety Circuit
The defrost control incorporates a pressure switch
safety circuit that allows the application of up to two
optional pressure switches; high pressure and/or loss
of charge. See figure 1. During a demand cycle, the
defrost control will lock out the unit on the third
instance that the unit goes off on any pressure switch
wired to this circuit. The diagnostic LEDs will display a
pattern for a lockout pressure switch on the third
open pressure switch occurrence. See table 1. The
unit will remain locked out until the switch is reset.
Remove factory-installed jumper before connecting
optional pressure switches to control board. When
two pressure switches are used, wire each switch to
one set of terminals PS1 and PS2 on the defrost
control board. See figure 1. When only one pressure
switch is used, wire the switch to the two outside
terminals of the pressure switch connections.
NOTE: If not using a pressure switch, the
factory-installed jumper wire must be connected.
Diagnostic LEDs
The defrost board uses two LEDs for diagnostics.
The LEDs flash a specific sequence according to the
condition.
TABLE 1
DEFROST CONTROL BOARD DIAGNOSTIC LED
MODE LED 1 LED 2
Normal Operation/ Flash together Flash together
Power to board with LED 2 with LED 1
Alternating Alternating
_me Delay
To Protect Compressor Flashes Flashes
with LED 2 with LED 1
Pressure Switch Open Off On
Pressure Switch Lockout On Off
Board Malfunction On On
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