Carrier 48HG014 Controls Operation And Troubleshooting

Contents

Carrier 48HG014 Controls Operation And Troubleshooting Manual pdf 2 page image

2from thermistors T1 through T5 and transducers T6 throughT8. See Table 2. The MBB also receives the Current Sensorinputs for compressors A1, B1 and C1 and other discrete ordigital inputs. See Table 3. The MBB reads space temperature(SPT) from either a T55, T56 or T58 device and space temper-ature offset (SPTO) from a T56 device. See Table 4 and Field-Installed Accessories section below. The MBB controls 11 re-lays. See Table 5.Economizer Control Board (ECB) — The ECB con-trols the economizer actuator. See Fig. 6. Relay 6 on the ECBsupplies 24 VAC to the actuator. The control signal from theECB uses the Belimo communication protocol. The ECB hasinputs for Indoor Air Quality (IAQ), Outdoor Air Quality(OAQ), and enthalpy. See Table 4. It also controls two powerexhaust motors (PE1 and PE2). See Table 5.By communicating with the ECB, the economizer actuatoris able to provide the damper position and diagnostic informa-tion to the ComfortLink controller. The damper position is dis-played as EC.AP under Outputs/Econ on the Scrolling Mar-quee. Diagnostic information is displayed via Alert T414.More information about these alarms is contained in theAlarms and Alerts section.Scrolling Marquee Display — This device is the key-pad interface used to access rooftop information, read sensorvalues, and test the unit. See Fig. 7. The marquee display is a4-key, 4-character, 16-segment LED (light-emitting diode)display. Eleven mode LEDs are located on the display as wellas an Alarm Status LED. See Marquee Display Usage sectionon page 11 for further details.Board Addresses — The Main Base Board (MBB) hasa 3-position instance jumper that is set at the factory to “1.”Do not change this setting. The ECB has a 4-position DIPswitch. Each DIP switch is set to “0” at the factory. Do notchange this setting.Control Module CommunicationRED LED — Proper operation of the control boards can bevisually checked by looking at the red status LEDs. Whenoperating correctly, the red status LEDs should blink in unisonat a rate of once every 2 seconds. If the red LEDs are not blink-ing in unison, verify that correct power is being supplied to allmodules. Also, be sure that the Main Base Board is suppliedwith the current software. If necessary, reload current software.If the problem still persists, replace the MBB. A board LEDthat is lit continuously or blinking at a rate of once per secondor faster indicates that the board should be replaced.GREEN LED — The MBB has one green LED. The LocalEquipment Network (LEN) LED should always be blinkingwhenever power is on. All other boards have a LEN LED thatwill blink whenever power is on. If LEN LED is not blinking,check LEN connections for potential communication errors(J3 and J4 connectors). Communication between modules isaccomplished by a 3-wire sensor bus. These 3 wires run inparallel from module to module. The J4 connector on the MBBprovides both power and communication directly to themarquee display.YELLOW LED — The MBB has one yellow LED. TheCarrier Comfort Network (CCN) LED will blink during timesof network communication.Carrier Comfort Network Interface — The 48/50HGunits can be connected to the CCN if desired. The communica-tion bus wiring is a shielded, 3-conductor cable with drain wireand is field supplied and installed. See Table 6 for wiring infor-mation. The system elements are connected to the communica-tion bus in a daisy chain arrangement. The positive pin of eachsystem element communication connector must be wired to thepositive pins of the system elements on either side of it. This isalso required for the negative and signal ground pins of eachsystem element. Wiring connections for CCN should be madeat TB2. See Fig. 1 and 2. Consult the CCN Contractor's Manu-al for further information.NOTE: Conductors and drain wire must be 20-AWG (Ameri-can Wire Gage) minimum stranded, tinned copper. Individualconductors must be insulated with PVC, PVC/nylon, vinyl,Teflon, or polyethylene. An aluminum/polyester 100% foilshield and an outer jacket of PVC, PVC/nylon, chrome vinyl,or Teflon with a minimum operating temperature range of–20 C to 60 C is required. See Table 6.It is important when connecting to a CCN communicationbus that a color-coding scheme be used for the entire networkto simplify the installation. It is recommended that red be usedfor the signal positive, black for the signal negative and whitefor the signal ground. Use a similar scheme for cables contain-ing different colored wires.At each system element, the shields of its communicationbus cables must be tied together. If the communication bus isentirely within one building, the resulting continuous shieldmust be connected to a ground at one point only. If the commu-nication bus cable exits from one building and enters another,the shields must be connected to grounds at the lightningsuppressor in each building where the cable enters or exits thebuilding (one point per building only). To connect the unit tothe network:1. Turn off power to the control box.2. Cut the CCN wire and strip the ends of the red (+), white(ground), and black (–) conductors. (Substitute appropri-ate colors for different colored cables.)3. Connect the red wire to (+) terminal on TB2 of the plug,the white wire to COM terminal, and the black wire to the(–) terminal.4. The RJ14 CCN connector on TB2 can also be used, but isonly intended for temporary connection (for example, alaptop computer running Service Tool).5. Restore power to unit.Field-Installed AccessoriesSPACE TEMPERATURE SENSOR (T55) — The T55 SpaceTemperature Sensor (Part No. CEC0121448-01) is a field-installed accessory. The sensor is installed on a building interi-or wall to measure room air temperature. The T55 sensor alsoincludes an override button on the front cover to permit occu-pants to override the Unoccupied Schedule (if programmed).The jumper wire in the installer’s packet must be connectedbetween R and W1 when using a T55 device. See Fig. 8-10.SPACE TEMPERATURE SENSOR (T56) — The T56 SpaceTemperature Sensor (Part No. CEC0121503-01) is a field-installed accessory. This sensor includes a sliding scale on thefront cover that permits an occupant to adjust the space temper-ature set point remotely. The jumper wire in the installer’spacket must be connected between R and W1 when using aT56 device. See Fig. 8, 9, and 11.IMPORTANT: A shorted CCN bus cable will preventsome routines from running and may prevent the unitfrom starting. If abnormal conditions occur, unplug theconnector. If conditions return to normal, check theCCN connector and cable. Run new cable if necessary.A short in one section of the bus can cause problemswith all system elements on the bus.