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Charging
The XP16 unit is factory-charged with enough HFC-410A
refrigerant to accommodate a 15-foot length of refrigerant
piping. Charge should be checked and adjusted using the
tables provided on the charging procedure sticker on the
unit access panel. Detailed information is given in the
XP16 Installation and Service Procedures manual, which
is available on DaveNet.
System Configuration
IMPORTANT
Some scroll compressor have internal vacuum protector
that will unload scrolls when suction pressure goes
below 20 psig. A hissing sound will be heard when the
compressor is running unloaded. Protector will reset
when low pressure in system is raised above 40 psig. DO
NOT REPLACE COMPRESSOR.
This section addresses:
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Unit components (sensors, temperature switch, pres
sure switches and demand defrost control)
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Second-stage operation
UNIT COMPONENTS
Demand Defrost Control (A108)
The demand defrost control measures differential temper
atures to detect when the system is performing poorly be
cause of ice build-up on the outdoor coil. The controller
self-calibrates
when the defrost system starts and after
each system defrost cycle. The demand defrost control's:
components are shown in figure 15.
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Demand defrost control connections, jumpers and
LED locations are shown in figure 15.
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Demand defrost control connections, jumpers and
LED descriptions are listed on table 2.
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Demand defrost control status, fault and lockout LEDs
are listed in table 3.
24V TERMINAL STRIP
CONNECTIONS (P2)
DIAGNOSTIC LEDS
(DS1 AND DS2)
PRESSURE SWITCH
CIRCUIT
CONNECTIONS
TEST PINS (P1)
Note - Component locations vary by board manufacturer.
SENSOR PLUG IN
(COIL AND
AMBIENT
SENSORS) (P4)
REVERSING VALVE
(O OUT)
DELAY PINS
(P5)
LOW AMBIENT
THERMOSTAT PINS
(P3)
DEFROST TERMINATION
PIN SETTINGS (P1)
Demand Defrost
Control (A108)
FIGURE 15
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