Filter Drier; Protective Devices; Relief Devices; Control Circuit, 24- -V - Carrier 48PG03-16 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

Filter Drier

Replace whenever refrigerant system is exposed 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 on every unit.

Protective Devices

Compressor Rotation
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 (3-phase units only) will not detect current.
See the Current Sensor section below for more information.
Current Sensor (CS) (3- -Phase Units Only)
The purpose of the CS is to detect losses in compressor power.
After detecting a loss in compressor power, unit control locks out
the compressor for 15 minutes. After 15 minutes, the alarm will
automatically reset. If this alarm occurs 3 times consecutively, the
compressor will remain locked out until an alarm reset is initiated
via CCN or manually via the Scrolling Marquee display (see
Alarms and Alerts section for more details).
Evaporator Fan Motor Protection
Indoor-fan motors less than 5 hp are equipped with internal
overcurrent and overtemperature protection. Protection devices
reset automatically. Disconnect and lock out power when
servicing motor. Indoor-fan motors 5 hp and larger are equipped
with a manual reset, calibrated trip, magnetic circuit breaker and
overcurrent protection. 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.
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 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 suction line service port. Protect
joint during brazing operations near joint.

Control Circuit, 24- -V

Each control circuit is protected 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. The
IGC error codes are shown in Table 98.
121