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Filter Drier —
Replace whenever refrigerant system is ex-
posed to atmosphere. Only use factory specified liquid-line
filter driers with working pressures no less than 650 psig. Do
not install a suction-line filter drier in liquid line. A liquid-line
filter drier designed for use with Puron® refrigerant is required
for each circuit.
Protective Devices
COMPRESSOR PROTECTION
Overcurrent — Each compressor has internal line break motor
protection.
Overtemperature — Each compressor has an internal protector
to protect it against excessively high discharge gas temperatures.
High-Pressure Switch — If the high-pressure switch trips, the
compressor will shut down and the current 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 alarm 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 Alarms and
Alerts section on page 54 for more details).
EVAPORATOR FAN MOTOR PROTECTION — A manu-
al 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-fan motor is internally protected against
overtemperature.
Fuses are also located in the control box and feed 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 will be shut down. After
15 minutes, the alarm 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 damage from excessive 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
before resetting.
Replacement Parts —
A complete list of replacement
parts may be obtained from any Carrier distributor upon
request.
Diagnostic LEDs —
The IGC control board has a LED
for diagnostic purposes. See Heating Troubleshooting section
on page 60 for more information.
Summary of Contents for 48PG24
Page 68: ...68 Fig 14 Low Voltage Control Schematic 48PG20 28 Units without Humidi MiZer System a48 7627...
Page 69: ...69 Fig 15 Low Voltage Control Schematic 48PG20 28 Units with Humidi MiZer System a48 8227...
Page 70: ...70 Fig 16 Low Voltage Control Schematic 50PG20 28 Units without Humidi MiZer System a48 7778...
Page 71: ...71 Fig 17 Low Voltage Control Schematic 50PG20 28 Units with Humidi MiZer System a50 8101...
Page 72: ...72 Fig 18 Power Schematic Units without Humidi MiZer System a48 7628...
Page 73: ...73 Fig 19 Power Schematic Units with Humidi MiZer System a48 8228...
Page 74: ...74 Fig 20 Component Arrangement Units without Humidi MiZer System a48 8229...
Page 75: ...75 Fig 21 Component Arrangement Units with Humidi MiZer System a48 8230...
Page 105: ......