Carrier 30GTN Service And Troubleshooting Manual

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MAJOR SYSTEM COMPONENTSGeneral — The 30GTN,R air-cooled reciprocating chill-ers contain the ComfortLink™ electronic control system thatcontrols and monitors all operations of the chiller.The control system is composed of several components aslisted in the sections below. See Fig. 1 for typical controlbox drawing. See Fig. 2-4 for control schematics.Main Base Board (MBB) — See Fig. 5. The MBB isthe heart of the ComfortLink control system. It contains themajor portion of operating software and controls the opera-tion of the machine. The MBB continuously monitors input/output channel information received from its inputs and fromall other modules. The MBB receives inputs from ther-mistors T1-T6, T9, and T10. See Table 2. The MBB alsoreceives the feedback inputs from compressors A1, A2, B1and B2, and other status switches. See Table 3. The MBBalso controls several outputs. Relay outputs controlled by theMBB are shown in Table 4. Information is transmitted be-tween modules via a 3-wire communication bus or LEN (Lo-cal Equipment Network). The CCN (Carrier Comfort Net-work) bus is also supported. Connections to both LEN andCCN buses are made at TB3. See Fig. 5.Expansion Valve (EXV) Board — The electronicexpansion valve (EXV) board receives inputs from ther-mistors T7 and T8. See Table 2. The EXV board commu-nicates with the MBB and directly controls the expansionvalves to maintain the correct compressor superheat.Compressor Expansion Board (CXB) — The com-pressor expansion board (CXB) receives the feedback in-puts from compressors A3, B3 and A4. See Table 3. The CXBboard communicates the status to the MBB and controls theoutputs for these compressors. The CXB board can also beused as an accessory to control up to two field-installed ac-cessory unloaders on 080-110, 130 (60 Hz), and 230B-315Bsizes.Scrolling Marquee Display — This device is the key-pad interface used for accessing chiller information, readingsensor values, and testing the chiller. The marquee display isa 4-key, 4-character, 16-segment LED (light-emitting diode)display. Eleven mode LEDs are located on the display aswell as an Alarm Status LED. See Marquee Display Usagesection on page 29 for further details.Energy Management Module (EMM) — The EMMmodule is available as a factory-installed option or as a field-installed accessory. The EMM module receives 4 to 20 mAinputs for the temperature reset, cooling set point reset anddemand limit functions. The EMM module also receives theswitch inputs for the field-installed 2-stage demand limit andice done functions. The EMM module communicates the sta-tus of all inputs with the MBB, and the MBB adjusts thecontrol point, capacity limit, and other functions accordingto the inputs received.Enable/Off/Remote Contact Switch — The Enable/Off/Remote Contact switch is a 3-position switch used tocontrol the chiller. When switched to the Enable position thechiller is under its own control. Move the switch to the Offposition to shut the chiller down. Move the switch to theRemote Contact position and a field installed dry contact canbe used to start the chiller. The contacts must be rated fordry circuit application capable of handling a 5 vdc, 1 to20 mA load. In the Enable and Remote Contact (dry con-tacts closed) positions, the chiller is allowed to operate andrespond to the scheduling configuration, CCN configurationand set point data. See Fig. 6.Emergency On/Off Switch — The Emergency On/Off switch should only be used when it is required to shutthe chiller off immediately. Power to the MBB, EMM, CXB,and marquee display is interrupted when this switch is offand all outputs from these modules will be turned off. TheEXV board is powered separately, but expansion valves willbe closed as a result of the loss of communication with theMBB. There is no pumpout cycle when this switch is used.See Fig. 6.Reset Button — A reset button is located on the fuse/circuit breaker panel for unit sizes 130-210 and associatedmodules. The reset button must be pressed to reset eitherCircuit Ground Fault board in the event of a trip.Board Addresses — The Main Base Board (MBB) hasa 3-position Instance jumper that must be set to ‘1.’All otherboards have 4-position DIP switches. All switches are set to‘On’ for all boards.Control Module CommunicationRED LED — Proper operation of the control boards can bevisually checked by looking at the red status LEDs (light-emitting diodes). When operating correctly, the red status LEDsshould be blinking in unison at a rate of once every 2 sec-onds. If the red LEDs are not blinking in unison, verify thatcorrect power is being supplied to all modules. Be sure thatthe Main Base Board (MBB) is supplied with the currentsoftware. If necessary, reload current software. If the prob-lem still persists, replace the MBB. A board LED that is litcontinuously or blinking at a rate of once per second or fasterindicates 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 LEDwhich should be blinking whenever power is on. Check LENconnections for potential communication errors at the boardJ3 and/or J4 connectors. Communication between modulesis accomplished by a 3-wire sensor bus. These 3 wires runin parallel from module to module. The J4 connector on theMBB provides both power and communication directly tothe marquee display only.YELLOW LED — The MBB has one yellow LED. TheCarrier Comfort Network (CCN) LED will blink during timesof network communication.Carrier Comfort Network (CCN) Interface — The30GTN,R chiller units can be connected to the CCN if de-sired. The communication bus wiring is a shielded, 3-conductorcable with drain wire and is supplied and installed in thefield. The system elements are connected to the communi-cation bus in a daisy chain arrangement. The positive pin ofeach system element communication connector must be wiredto the positive pins of the system elements on either side ofit. This is also required for the negative and signal groundpins of each system element. Wiring connections for CCNshould be made at TB3. Consult the CCN Contractor’s Manualfor further information.NOTE: Conductors and drain wire must be 20 AWG (Amer-ican Wire Gage) minimum stranded, tinned copper. In-dividual conductors must be insulated with PVC, PVC/nylon, vinyl, Teflon, or polyethylene. An aluminum/polyester100% foil shield and an outer jacket of PVC, PVC/nylon,chrome vinyl, or Teflon with a minimum operating tem-perature range of −20 C to 60 C is required. Wire manu-factured by Alpha (2413 or 5463), American (A22503), Belden(8772), or Columbia (02525) meets the above mentionedrequirements.3