Carrier 48/50PD05 Relief Devices, Compressor Sound Shield, Control Circuit, Replacement Parts

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.

COMPRESSOR BASE

SHIELD

Cut Compressor Base Sound Shield along dotted lines

Remove this compressor mounting bolt and grommet at this location.

Slide Compressor Base Sound Shield in this direction.

Fuses are 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 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.

Compressor Sound Shield

The 48/50PD units are equipped with a compressor sound shield. The sound shield has two parts, the compressor jacket encloses the shell of the compressor and the base shield is installed between the bottom of the compressor and the unit base pan. The sound shield reduces the difference in noise levels as the compressor loads and unloads in the frequency ranges of 200 to 2000 Hz. Since the human speech occurs in the 200 to 2000 Hz frequency ranges the sound shield reduces the speech annoyance caused by the loading and unloading of the compressor.

The compressor jacket is held closed around the compressor by Velcro tape. To remove the compressor jacket, separate the Velcro along the side and top of the compressor. Slide the jacket toward the back of the compressor to remove the jacket. Make sure the jacket is reinstalled after servicing or replacing the compressor.

The compressor base shield is accessible when the compressor is removed. To remove the base shield without removing the compressor, remove one front compressor mounting bolt and grommet. At the three remaining compressor mounting grommets, cut the sound shield so that the base shield can be slid in the direction of the compressor mounting bolt and grommet that was removed. (See Fig. 39.) Cut replacement base shield along dotted lines as shown in Fig. 39 and reinstall in reverse direction. When installing the base shield, place the soft side facing upward. Reinstall compressor mounting grommet and bolt.

C08664

Fig. 39 - Base Sound Shield

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 MBB, ECB, AUX1, IGC and DSC control boards have LED lights for diagnostic purposes. The meanings and error codes can be found in the the troubleshooting section of this manual.

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