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The TEST mode may be started at anytime. If the jumper
is in the TEST position at power-up or for longer than
five minutes, the control will ignore the TEST selection
and will default to a 90 minute interval.
Time-Delay
The timed-off delay is five minutes long. The delay fea
ture is provided to help protect the compressor in
cased of an interruption in power to the unit or when a
pressure switch resets.
Pressure Switch Safety Circuits
The defrost control incorporates a pressure switch safe
ty circuit that allows the application of an additional
pressure switch; high pressure switch (S4) is factory-
wired to this circuit. See figure 9. PS1 and PS2 terminals
are wired in series with a jumper internal to the control
board. This feature is available on all units.
During one demand cycle, the defrost control will lock
out the unit on the third instance that the unit goes off
on any auto-reset pressure switch wired to this circuit.
The diagnostic LEDs will display a pattern for a locked
out pressure switch on the third open pressure switch
occurrence. See table 7. The unit will remain locked out
until power is broken then remade to the control.
For HP25-211/461 units, the PS2 safety circuit termi
nals are connected to the compressor thermostat. An
optional loss of charge switch may be field-installed by
connecting it in series with the other switches. See unit
wiring diagram.
HP25-511/651 units are equipped with a factory-
installed jumper over the two safety circuit PS2 termi
nals on the defrost board. If using an additional pres
sure switch, remove jumper before connecting
additional switch to control board. If no additional
switch is needed,
DO NOT REMOVE JUMPER
. Unit will
not operate without jumper in place in this case.
For three-phase units, the factory-installed high pres
sure switch is connected to the two outside terminals
of the pressure switch connections. If adding another
pressure switch, remove lead from outer PS2 terminal
and connect it to inside terminal of PS1. Connect addi
tional pressure switch leads to PS2 set of safety circuit
terminals. See figure 9.
DEFROST CONTROL BOARD
FIGURE 9
24V TERMINAL
STRIP
CONNECTIONS
DIAGNOSTIC
LEDs
PRESSURE
SWITCH
SAFETY CIRCUIT
CONNECTIONS
S4
S5
S4
FACTORY CONNECTION FOR
THREE-PHASE UNITS ONLY
FACTORY CONNECTIONS FOR
HP25-211/461 UNITS ONLY
DEFROST
INTERVAL
TIMING PINS
FACTORY-INSTALLED
JUMPER
HP25-511/651 ONLY.
(Remove to add
pressure switch)
AMBIENT
THERMISTOR
CONNECTION
High Pressure
Compressor
Thermostat
S4
FACTORY CONNECTIONS FOR
HP25-511/651 UNITS ONLY
High Pressure
To add additional pressure switch, remove jumper and
connect optional switch leads to PS2 terminals. If no
other pressure switch is added, jumper must stay in
place for proper unit operation.
To add additional pressure switch, remove lead from
outer PS2 terminal and connect to inside PS1 terminal.
Connect optional switch leads to PS2 terminals.
NOTE- There is an internal jumper between inside PS1 and PS2 terminals.
High Pressure
SERVICE LIGHT
CONNECTION
To add additional pressure switch, such as loss of
charge switch, wire it in series with the two factory-
installed switches. See unit wiring diagram for details.
