Filter Drier; Service; Protective Devices; Relief Devices - Carrier 50PG20-28 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

Filter Drier -- Replace whenever ref-igerant system is ex-
posed to atmosphere. Only use factory specified liquid-line
tilter driers with working pressures no less than 650 psig. Do
not install a suction-line ftter drier in liquid line. A liquid-line
flter drier designed for use with Puron,_R) refi-igerant is required
for ca& circuit.
Protective Devices
COMPRESSOR PROTECTION
Overcu_rrent Each compressor has internal line break motor
protection.
Overtemperature Each compressor has an intemal protector
to
protect it against excessively high dischmge gas temperatures.
Hi_h-Pressure Switch If the high-pressure switch trips, the
compressor will shut down and the currem sensor will not
detect
current. See the Current Sensor
section below
for more
information.
Current Sensor
(CS)
The purpose
of the CS is to detect
losses in compressor power. After detecting a loss in compres-
sor power, unit control locks out the compressor for 15 min-
utes.
After 15 minutes, the alarm will
automatically reset.
If
this atann occurs 3 times consecutively, the compressor will re-
main locked out until an alarm reset is initiated via CCN or
manually via the Scrolling Marquee display (see Atanns and
Alerts section on page 54 for more details).
EVAPORATOR FAN MOTOR PROTECTION A manu-
at reset, calibrated trip, magnetic circuit breaker protects
against overcurrent. Do not bypass connections or increase the
size of the breaker to correct trouble. Determine the cause and
correct it before resetting the breaker.
CONDENSER-FAN MOTOR PROTECTION Each
condenser-fro1 motor is internally protected against
overtemperature.
Fuses are also located in the control box and teed power to
the condenser fan motors. Always replace blown fuses with the
correct size fuse as indicated on the unit fuse label.
SATURATED SUCTION PRESSURE (SSP) If the SSP
for a particular circuit is reading below the alarm set point for
an extended period of time, that circuit wilt be shut down. After
15 minutes, the atann will automatically reset. If this alarm
occurs 3 times consecutively, the circuit will remain locked out
until an alarm reset is initiated via CCN or manually via the
Scrolling Marquee display (see Alarms and Alerts section on
page 54 for more details).
Relief Devices -- All units have relief devices to protect
against d,'unage tiom excessNe pressures (i.e., fire). These
devices protect the high and low side and are located at the suc-
tion line service port. Protect joint during brazing operations
near joint.
Control Circuit, 24-V-
Each control circuit is pro-
tected against overcurrent by a 3.2 amp circuit breaker.
Breaker can be reset. If it trips, determine cause of trouble
bel\)re resetting.
Replacement Parts -- A complete list of replacement
parts may be obtained tiom any Carrier distributor upon
request.
Diagnostic LEDs -- The IGC control board Ms a LED
for diagnostic purposes. See Heating Troubleshooting section
on page 60 for more information.
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