McQuay AGR 070AS Operation Manual
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McQuay AGR 070AS Operation Manual

Air-cooled reciprocating chiller, v60 hertz, english and metric global chiller line
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Installation, Operation and Maintenance Manual
Air-Cooled Reciprocating Chiller
AGR 070AS through 100AS
60 Hertz, English and Metric
Global Chiller Line
IOMM AGR-1
Group: Chiller
Part Number: 330145704
Effective: August 2001
Supersedes: IOMM AGR

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Summary of Contents for McQuay AGR 070AS

  • Page 1 Installation, Operation and Maintenance Manual IOMM AGR-1 Group: Chiller Part Number: 330145704 Effective: August 2001 Supersedes: IOMM AGR Air-Cooled Reciprocating Chiller AGR 070AS through 100AS 60 Hertz, English and Metric Global Chiller Line...

  • Page 2: Table Of Contents

    "McQuay" is a registered trademark of McQuay International  2001 McQuay International "Illustrations and data cover McQuay International products at the time of publication and we reserve the right to make changes in design and construction at anytime without notice." AGR 070A through 100A...

  • Page 3: Introduction

    Check all items carefully against the bill of lading. Inspect all units for damage upon arrival. Report shipping damage and file a claim with the carrier. Check the unit name plate before unloading, making certain it agrees with the power supply available. McQuay is not responsible for physical damage after unit leaves the factory.

  • Page 4: Installation

    Installation Note: Installation is to be performed by qualified personnel who are familiar with local codes and regulations. WARNING Sharp edges and coil surfaces are a potential hazard. Avoid contact with them. Handling Be careful to avoid rough handling of the unit. Do not push or pull the unit from anything other than the base.

  • Page 5: Location

    Location Unit Placement AGR units are for outdoor applications and can be mounted on a roof or ground level. Set units on a solid and level foundation. For roof mounted applications, install the unit on a steel channel or I- beam frame to support the unit above the roof.
  • Page 6 Figure 3, Clearance Requirements Do not block the flow of air to DISCHARGE DISCHARGE and from the condenser coil. Restricting airflow or allowing air recirculation will result in a decrease in unit performance AIR FLOW and efficiency because AIR FLOW AIR FLOW discharge pressures are 10 FT.

  • Page 7: Vibration Isolators

    See Dimensional Data for dimensions required to secure each isolator to the mounting surface. The spring flex isolators are white type CP2-32, McQuay kit number 350014821, includes four spring isolators assemblies. Figure 4, Isolator Locations (4 and 6 fan units)

  • Page 8: Water Piping

    Water Piping Local authorities can supply the installer with the proper building and safety codes required for safe and proper installation. Install piping with minimum bends and changes in elevation to minimize pressure drop. Consider the following when installing water piping: Vibration eliminators to reduce vibration and noise transmission to the building.

  • Page 9: Flow Switch

    A flow switch is available from McQuay (part number 0017503300). It is a “paddle” type switch and adaptable to any pipe size from 3” (76mm) to 8” (203mm) nominal. Certain minimum flow rates are required to close the switch and are listed in Table 3.

  • Page 10: Glycol Solutions

    Figure 7, Refrigerant Piping (Some Components Are Optional) Glycol Solutions The system glycol capacity, glycol solution flow rate in GPM, and pressure drop through the cooler may be calculated using the following formulas and data from Table 4 or Table 5. Note: The procedure Capacity -- Find the reduced capacity by multiplying the chiller’s capacity with water by the does not specify the...
  • Page 11 CAUTION Do not use an automotive grade antifreeze. Industrial grade glycols must be used. Automotive antifreeze contains inhibitors which will cause plating on the copper tubes within the chiller evaporator. The type and handling of glycol used must be consistent with local codes.

  • Page 12: Evaporator Water Flow/Pressure Drop

    Evaporator Water Flow/Pressure Drop Evaporator flow rate must fall between the minimum and maximum values shown in the evaporator pressure drop table on page 12. Varying chilled water flow through the evaporator while the compressor(s) are operating is not recommended. Figure 8, Pressure Drop Curve 090 - 100 075 - 085...

  • Page 13: Physical Data

    Physical Data Table 7, AGR 070AS – AGR 085AS AGR MODEL NUMBER PHYSICAL DATA STANDARD EFFICIENCY 070AS 075AS 080AS 085AS BASIC DATA Ckt.1 Ckt.2 Ckt.1 Ckt.2 Ckt.1 Ckt.2 Ckt.1 Ckt.2 Unit Capacity @ ARI Conditions (1), Tons (kW) 67.5 (237.6) 70.1 (246.7)
  • Page 14 Table 8, AGR 090A – AGR 100A PHYSICAL DATA AGR MODEL NUMBER STANDARD EFFICIENCY 090AS 095AS 100AS BASIC DATA Ckt.1 Ckt.2 Ckt.1 Ckt.2 Ckt.1 Ckt.2 Unit Capacity @ ARI Conditions (1), Tons (kW) 86.5 (304.1) 93.4 (328.4) 99.3 (349.1) Number Of Refrigerant Circuits Unit Operating Charge, R-22, lb.

  • Page 15: Electrical Data

    Electrical Data Field Wiring CAUTION Internal power wiring to the compressors for single and multiple point option are different. Field wiring must be installed according to unit wiring diagram. Wiring must comply with all applicable codes and ordinances. Warranty is void if wiring is not in accordance with specifications.
  • Page 16 Table 9, 60 Hz, Single Point Power Electrical Data POWER SUPPLY Minimum Max. Fuse Field Wire Conduit Hub Circuit Unit Volts Ampacity HACR Breaker Wire Nominal Size Quantity Quantity (MCA) Size Gauge Size 2.50 2.50 070AS 2.00 070AM 1.50 1.25 3.00 2.50 075AS...
  • Page 17 Table 10, 60 Hz, Compressor and Condenser Fan Motor Amp Draw Rated Load Amps Locked Rotor Amps No. Of Compressors Compressors Unit Volts Motors Motors Across-The-Line Part Winding (1) Size (Each) Motors (Each) No. 1 No. 2 No. 1 No. 2 30.5 N.A.
  • Page 18 Table 11, 60 Hz Single Point Power, Field Wiring Data Wiring to Standard Wiring to Optional Power Block Non-Fused Disconnect Switch Unit Volts Terminal Connector Wire Range Terminal Connector Wire Range Size Amps (Copper Wire Only) Amps (Copper Wire Only) # 4 - 400 MCM 250 - 500 MCM # 4 - 400 MCM...
  • Page 19 Notes for “Electrical Data Single Point” Power: 1. Unit wire size ampacity (MCA) is equal to 125% of the largest compressor-motor RLA plus 100% of RLA of all other loads in the circuit including the control transformer. 2. If the control transformer option is furnished, a separate 115v power is not required. 3.
  • Page 20 Figure 9, Typical Field Wiring with Global UNT Controller AGR 070A through 100A IOMM AGR-1...
  • Page 21 Figure 10, Typical Field Wiring Diagram with MicroTech Controller IOMM AGR-1 AGR 070A through 100A...
  • Page 22 Figure 11, Standard Single-Point Connection with FanTrol AGR 070A through 100A IOMM AGR-1...
  • Page 23 Figure 12, Standard Single-Point Connection with Optional SpeedTrol IOMM AGR-1 AGR 070A through 100A...
  • Page 24 Figure 13, Unit Control Schematic (2 compressor UNT) AGR 070A through 100A IOMM AGR-1...
  • Page 25 Figure 14, Staging Schematic (2 compressor 4-stage UNT) IOMM AGR-1 AGR 070A through 100A...
  • Page 26 Figure 15, Staging Schematic (2 compressor 6-stage UNT) AGR 070A through 100A IOMM AGR-1...
  • Page 27 Figure 16, MicroTech Controller Schematic IOMM AGR-1 AGR 070A through 100A...
  • Page 28 Figure 17, Unit Control Schematic (MicroTech) AGR 070A through 100A IOMM AGR-1...
  • Page 29 Figure 18, Staging Schematic (4-stage MicroTech) IOMM AGR-1 AGR 070A through 100A...
  • Page 30 Figure 19, Staging Schematic (6-stage MicroTech) AGR 070A through 100A IOMM AGR-1...
  • Page 31 Figure 20, Unit Control Schematic (2 compressor MicroTech) IOMM AGR-1 AGR 070A through 100A...
  • Page 32 Figure 21, UNT Instrument Layout See legend on page 34. AGR 070A through 100A IOMM AGR-1...
  • Page 33 Figure 22, MicroTech Instrument Layout See legend on page 34. IOMM AGR-1 AGR 070A through 100A...
  • Page 34 Figure 23, AGR Power Side Component Layout See legend on page 34. Figure 24, Component Layout Legend AGR 070A through 100A IOMM AGR-1...
  • Page 35 Figure 25, MicroTech Sensor Layout IOMM AGR-1 AGR 070A through 100A...

  • Page 36: Dimensional Data

    Dimensional Data Figure 26, Dimensions AGR 070AS 4” (107mm) (AGR055-060) 5” (127mm) (AGR065-070) VICTAULIC CONNECTIONS OUTLET FURNISHED WITH GROOVES INLET FOR VICTAULIC COUPLINGS BY OTHERS NOTE: 1. ALL DIMENSIONS IN INCHES (mm) 2. ALL UNITS HAVE (2) INDEPENDENT EVAPORATOR REFRIGERANT CIRCUITS...
  • Page 37 Figure 27, Dimensions AGR 075AS through 100AS 5” (127mm) (AGR075-100) VICTAULIC CONNECTIONS NOTE: FURNISHED WITH GROOVES 1. ALL DIMENSIONS IN INCUES (mm) FOR VICTAULIC COUPLINGS 2. ALL UNITS HAVE (2) INDEPENDENT INLET OUTLET BY OTHERS REFRIGERANT CIRCUITS EVAPORATOR 2 REFRIGERANT CIRCUITS CONTROL BOX COIL HEADERS AT THIS END...

  • Page 38: Agr Unit Start-Up

    AGR Unit Start-Up Pre start-up The chiller must be inspected to ensure no components became loose or damaged during shipping or installation or during extended shut down periods. Water piping checkout 1. Check the pump operation and vent all air from the system. 2.

  • Page 39: Start-Up

    Be prepared to record all operating parameters required by the “Compressorized Equipment Warranty Form”. Return this information within 10 working days to McQuay International as instructed on the form to obtain full warranty benefits.

  • Page 40: Agr Unit Operation

    AGR Unit Operation Sequence of Operation Starting With control power on, 115Vac power is applied through F1 to the compressor crankcase heaters and control transformer T2. T2 supplies 24Vac to the Global UNT controller. The green light on the Global UNT controller will begin to flash. The panel Alarm Light will illuminate. Put the System Switch S1 into the AUTO position.

  • Page 41: Hot Gas Bypass (Optional)

    Software Description (Global UNT Interface Kit required to read or change variables) Variable Description Default Value Range Name LPSS Low Pressure Starting Setpoint 10 psi 5 to 15 psi SLPT Starting Low Pressure Time 260 sec 90 to 300 seconds Calculated (LPSS-LPSD) MLPS Minimum Low Pressure Setpoint...

  • Page 42: System Adjustment

    System Adjustment To maintain peak performance at full load operation, the system superheat and liquid subcooling may require adjustment. Read the following subsections closely to determine if adjustment is required. Liquid Sightglass and Moisture Indicator The moisture indicator color is an indication of the dryness of the system and is extremely important when the system has been serviced.

  • Page 43: Unt Controller Operation

    UNT Controller Operation This section provides setup and troubleshooting information for the Global UNT controller. All operational descriptions are based on the Global UNT software SURE4-2A. Operational characteristics may vary with other versions of software. General Description The Global UNT is a microprocessor based leaving water controller designed for multiple stage operation.
  • Page 44 The “setpoint” control knob adjusts the leaving water setpoint. The “Control Band” knob adjusts the controller temperature control band. To set, divide the chilled water temperature range by the number of capacity steps and add 0.5°F for the minimum setting. Example: Evaporator water temperature range = 10°F from 54°F to 44°F Capacity steps = 6...

  • Page 45: Controller Inputs /Outputs

    The Global UNT controller can be connected to an IBM or IBM compatible computer for setpoint changes and downloading of different software’s. A Global UNT Interface Kit is available from your local McQuay Sales Representative. Software Identification Control software is factory installed and tested in each panel prior to shipment. The software is identified by a program code which is printed on the a small label attached to the controller.
  • Page 46 Digital Inputs Note: All Digital Inputs are 24 VAC supplied by transformer T2 in the control panel. Do not use inputs from another power supply external to the unit. This can cause failure of the Global UNT controller. Table 13, Digital Inputs Input Description Location...
  • Page 47 Figure 28, Outside Air Reset LWRB LWSP OALL OAHL OARB (OALL=OAHL - OARB) As the OAT increases above the Outdoor Air Low Limit (OALL), the Actual Leaving Water Setpoint is decreased from its Leaving High Limit (Leaving Water Setpoint plus Leaving Reset Band) to the Leaving Water Setpoint.
  • Page 48 When Return Water Reset is chosen, a Fail Smart Logic option is also available. This option works as follows. If the Leaving Water Sensor (AI-1) becomes unreliable, the controller switches from Leaving Water control to Return Water control. Actual Return Water Setpoint equals Leaving Water Setpoint (AI-4) plus an adjustable Leaving Water Setpoint Offset.

  • Page 49: Additional Unt Controller Features

    Additional UNT Controller Features Remote Stop/Start When the remote stop/start switch is open, the controller will be in the unoccupied mode. The unit will be enabled when the remote start / stop switch is closed and will control at the leaving water temperature setpoint.
  • Page 50 energized, the operating compressor on that refrigerant circuit will operate until the low pressure switch opens and stops that compressor. The compressor will cycle on if the evaporator pressure exceeds the low pressure cut-in value. After a two hour time delay, the compressor will start again to pump down the circuit (limited recycling pumpdown).

  • Page 51: Alarms

    Head Pressure Control There are two or three condenser fans per refrigerant circuit. These fans are cycled on and off according to the circuit’s condenser pressure. Fan #1 of a refrigerant circuit will start when the compressor of that refrigerant circuit has started. This fan will not cycle off until the circuit is stopped.

  • Page 52: Zone Terminal (Optional)

    ZONE TERMINAL (optional) The Zone Terminal (ZT) is a hand-held or unit mounted device that monitors and adjusts your McQuay Global Reciprocating Chiller information. A standard telephone-style jack directly connects the ZT to the McQuay Global UNT controller. Features •...
  • Page 53 You can simultaneously monitor the chiller in three ways: • Monitor up to three settings/sensed values. A maximum of six items are accessible in each of the three displays. • Read the symbols to the right of the display numbers to learn the on/off status of various inputs, outputs, or modes (| = On status;...
  • Page 54 McQuay Global Reciprocating Controller Connection A standard telephone-style jack connects the ZT to a McQuay Chiller Controller directly. Figure 33, Connecting ZT to a Global UNT Controller Using 6 to 8 Pin Cable 1 2 3 4 5 6 7 8...

  • Page 55: Zone Terminal Glossary

    ZT has processed your adjustment. 5. Press any of the Display Buttons to make other adjustments, and repeat Steps 2 and 3. Adjustable Points The following McQuay Global Reciprocating Chiller points are adjustable by the Zone Terminal. Table 17, Adjustable Points TEMPLATE...
  • Page 56 Lvg Low Lim SP - Adjustable from 20°F - 40°F (default is 20°F). This safety that will shut the chiller off based on the leaving water temperature going below this setpoint. SoftSta Capcty - Adjusts the ramping of steps from 0% - 100% (default is 50%). SoftStart Time - Adjustable ramping time from 0 - 20 minutes (default is 2 minutes).

  • Page 57: Unt Controller Troubleshooting Chart

    UNT Controller Troubleshooting Chart PROBLEM POSSIBLE CAUSES CORRECTIVE ACTIONS Compressor Main switch, circuit breakers open. Close switch. Will Not Run Fuse blown. Check electrical circuits and motor winding for shorts or grounds. Possible overloading. Replace fuse or reset breakers after fault is corrected. Overloads are auto reset.

  • Page 58: Microtech Controller Installation And Operation

    Important operating conditions at the time of the alarm are retained in the controller’s memory to aid in troubleshooting and unit diagnostics. McQuay MicroTech Monitor software is available for remote adjustment and monitoring of the chiller.

  • Page 59: Interlock Wiring

    All control and safety set points must be checked by the installing contractor and adjusted as necessary before starting the unit. Controllers for McQuay chillers have default set points. Refer to the menu items listed below.

  • Page 60: Chilled Water Flow Switch

    Power Wiring The installing contractor provides the unit voltage power source, disconnect, fuses and necessary wiring for these circuits. All wiring must conform to the National Electrical Code and applicable local building codes. If the control power source (120Vac) or the evaporator heater power source (120Vac) or both are supplied from a separate external supply, remove wires 540 and 545 as indicated on the field wiring diagram.
  • Page 61 External Alarm Annunciator Circuitry An audible alarm can be connected to the Alarm Output terminals #19 and #28 of TB-3 of the control panel and is highly recommended to make certain the operator is alerted to any alarm condition. This output can also be used to alert a building automation system or other controls as required.
  • Page 62 Digital Inputs All Digital Inputs are 24 Vac. At 7.5 Vac to 24 Vac the digital input contacts are considered closed. Below 7.5 Vac, the contracts are considered open. See Table 19 for details and operating characteristics. Table 19, Digital Inputs Input Description Circuit...
  • Page 63 (21°F + 2°F = 23°F; 23°F = 46psig) Network A network refers to a McQuay MicroTech control panel (CSC or RMS) that can provide controlling functions to several McQuay chillers. One function is to control the chiller leaving water temperature according to some control logic in the network control panel.

  • Page 64: Manual Operation

    Soft Loading Soft loading limits the number of available stages when the unit is started to prevent excessive power consumption and possible overshoot of the leaving water temperature set point. Soft loading is in effect whenever the unit is started from an “off” cycle. On initial start-up, the chiller will turn on the chilled water pump and sample the loop water temperature for a time equal to the Load Delay set point (“LoadDelay”).

  • Page 65: Head Pressure Control

    Thus, the alarm must be manually cleared. When a McQuay Chiller with a MicroTech controller is used with the McQuay RMS (Remote Monitoring and Sequencing) Panel, the user must note that alarm nomenclature varies. The RMS has three possible categories of alarms: faults, problems, and warnings.

  • Page 66: Sequence Of Operation

    Circuit Alarm Conditions The “Circuit Alarm Conditions” are those alarms which only affect one circuit and can stop the compressors of that circuit. These alarms are: • Compressor Motor Protection • High Condenser Pressure • Mechanical High Pressure Switch • Low Evaporator Pressure •...
  • Page 67 Assuming none of the above “OFF” conditions are true, the controller will examine the internal time clock schedule to determine if the chiller should start. The operating mode will be OFF:TimeClock if the time schedule indicates an “OFF” time period. Start - Up If none of the “OFF”...

  • Page 68: Start-Up And Shutdown

    Start-Up and Shutdown Pre-Start Checkout Configuration default set points are entered at the factory and all values must be checked and reset for each installation. Make sure the field wiring for all flow switches, interlocks or jumpers matches the connections detailed on the field wiring drawing. Setting of the HEX Address Switches The controller HEX address switches for each unit determine its logical address in a MicroTech network or in an Open Protocol network.

  • Page 69: Keypad / Display

    above the LPCutIn value, a compressor on the lead circuit will start. Refer to the unit staging schematic to determine which LED is associate to a compressor. The controller will stage up and down to maintain the desired leaving water temperature. Temporary Shutdown Close both pumpdown switches.
  • Page 70 Menu Structure (general description) The information stored in the MicroTech controller can be accessed through the keypad using a tree- like structure. This tree structure is divided into Categories, Menus and Menu Items. There are three categories that make up the tree structure: STATUS, CONTROL, and ALARM. Each category is divided into Menus and each Menu into Menu Items.
  • Page 71 Keypad Key Functions The MicroTech keypad consists of twelve pressure sensitive membrane switches (Figure 34). These keys are used to step through, access, and manipulate the information in the MicroTech controller tree structure. The keypad keys are divided into four groups with two or four keys in each. These groups of keys and their functions are described below.

  • Page 72: Menu Descriptions

    Decr. - When changing the value of a menu item entry, pressing “DECR. -” shifts the menu item display line to the next lower value or previous available selection. Enter - Once a change has been made to a desired value, pressing “ENTER” locks in the new value. Clear - Pressing “ALARMS”...
  • Page 73 Menu #6: Circuit 62 Pressures—The circuit #2 evaporator and condenser refrigerant pressure readings are displayed under this menu. The calculated minimum and maximum condenser pressure values are also shown. Menu #7 : Circuit #l Temperatures—The circuit #I refrigerant temperatures are calculated from their corresponding pressure sensors and displayed here.
  • Page 74 If the 4-20 milliamp reset option is enabled, the controller will reset the leaving chilled water temperature to a higher value based on a percentage of the Maximum Chilled Water Reset set point ("MaxChWRst"). At 4mA or less, no reset will occur. At 20mA, the chilled water set point will be reset to a value equaling the Leaving Evaporator Water Set Point ("Lvg Evap") plus the value stored in the "MaxChWRst".
  • Page 75 Figure 35, Delta-T Setpoints for Chillers Menu #15: Softload Set Points—The controller can limit the number of available stages when the unit is initially started to prevent excessive power consumption and help control overshoot of the water temperature set point. The maximum number of stages will equal the Soft Load Maximum Stages for the time period defined in the softload timer set point.
  • Page 76 Press the Next Item key. The display will show the current Day, Hour, Minute and Second. If this information needs to be changed, follow the same procedure used to set the Date in the previous section. Menu #20 : Daily Schedule—This section will help you to set the Daily Start/Stop time for automatic operation of the chiller.
  • Page 77 Menus for the AGR MicroTech Controller Table 22, MENU 1 Chiller Status Table 25, MENU 4 Water Temp's Screen Display Screen Display OFF: Manual Mode Lvg Evap= xxx.x °F (°C) OFF: System Sw Short °F (°C) OFF: Remote Comm Open °F (°C) OFF: Remote Sw Ent Evap= xxx.x °F (°C) OFF: Time Clock...
  • Page 78 Table 28, MENU 7 Circ #1 Temp's Table 30, MENU 9 Chiller Amps Screen Display Screen Display Satur Evap=xxx°F (°C) PercentRLA=xxx% N/A **°F (°C) SuctLine = xxx.x°F (°C) Open °F (°C) Table 31, MENU 10 Comp RunHours Short °F (°C) Screen Display Super Ht =xxx.x°F (°C)
  • Page 79 Table 34, MENU 13 Control Mode Screen Display Factory Setpoint Range Manual Unit Off Automatic Manual Unit Off Manual Staging Manual Stage=xx 1 - 8 Table 35, MENU 14 Lvg Evap Spts Values for R-22 refrigerant, ( ) indicates Centigrade values Screen Display Factory Setpoint...
  • Page 80 Table 37, MENU 15 SoftLoad Spts Screen Display Factory Setpoint Range Time Left= xxmin SoftLoad= xx min 0 - 254 SoftLdMaxStg= x 1 - 4 LoadDelay= xxsec 0 - 254 Table 38, MENU 16 CompressorSpt Screen Display Factory Setpoint Range 1234 1432 2143...
  • Page 81 Table 43, MENU 20 Schedule Screen Display Factory Setpoint Range Override= xx.xx hr 0.00 Hr 00:00 - 63.50 NMPSchedule= N/A Sun 00:00-23:59 00:00 - 23:59 00:00 - 23:59 Mon 00:00-23:59 00:00 - 23:59 00:00 - 23:59 Tue 00:00-23:59 00:00 - 23:59 00:00 - 23:59 Wed 00:00-23:59 00:00 - 23:59...
  • Page 82 Table 47, MENU 23 Misc Setup Screen Display Factory Setpoint Range Unit Type= Air Cooled Units = English English English - Metric SpeedTrol = No No - Yes Power = 60 hz 60 - 50 Port A Baud=xxxx 9600 9600 - 2400 - 1200 Pre-Alarm=Blink Blink Blink - Open - Closed...

  • Page 83: Trouble Analysis For The Agr Microtech Controller

    Trouble Analysis for the AGR MicroTech Controller Microprocessor Control Board The Microprocessor Control Board (MCB) is shown in Figure 36. It contains a microprocessor that is preprogrammed with the software required to monitor and control the chiller. The various MCB connections and components are described below.
  • Page 84 1. The red (“Reset”) LED turns on and remains on for approximately 5 seconds. During this period the MCB performs a self-test. 2. The red LED turns off and the green (“Running”) LED turns on. This indicates that the microprocessor has passed the self-test and is functioning properly. 3.
  • Page 85 Communication Ports The MCB has two communication ports: port A and port B. Each port has six terminals and is set up for both the RS-232C and RS-485 data transmission interface standards. The male and female connectors for these ports are manufactured by AMP. Therefore, they are referred to as “AMP plugs” or “AMP connectors”...

  • Page 86: Test Procedures

    Test Procedures Status LED Diagnostics The MCB status LED indications can aid in controller diagnostics. If the status LEDs do not operate normally there is a problem with the MCB. Following are troubleshooting procedures for the various symptoms. Red LED Remains On If the red LED remains on after the 5-second self-test period, it is likely that the MCB is defective.
  • Page 87 6. Reconnect the analog input ribbon cable. Cycle power to the controller and check the power fuses. If both fuses are intact, go to step 7. If either fuse blows, check the ADI board, the connecting ribbon cable, and the field wiring for shorts.
  • Page 88 Figure 38, MCB Power Supply Terminals POWER FUSES [BUSSMAN GDC-T2A] Fuse F1 Fuse F2 9 8 7 6 5 4 3 2 1 AUX/OUT Troubleshooting the Keypad/Display Interface The Keypad/Display Interface is connected to the MCB via a ribbon cable and discrete wiring for the backlight.
  • Page 89 Troubleshooting Analog Inputs An analog input, such as a temperature sensor, is connected to the ADI board. The ADI board then conditions the analog input. The conditioned input is transferred to the MCB via a ribbon cable. Analog Input not Read by the MCB If the MCB appears to be functioning properly and the analog input is not being read by the MCB, perform the following procedure: 1.
  • Page 90 Figure 39, Output Board Relay Socket Fuse *250V ~ 50/60 Hz *120V ~ 50/60 Hz Test Resistor 330-680 Ohm WARNING Electric shock hazard. Can cause severe injury or death. Even when power to the panel is off, solid-state relay socket terminals 1 and 2 on the output board could be connected to high voltage.
  • Page 91 2. Remove power from the controller by placing CB1 to the OFF position. Disconnect at least one wire from the power input terminals of the Output Board. The resistance should not be less than 3000 ohms. If the resistance is greater than the acceptable value, go to step 3. If the resistance is less than the acceptable value, the Output Board is defective.
  • Page 92 3. Remove power from the controller by opening CB1. Try to improve the connections in the Aux/Out plug insulation displacement terminals by pressing down on the wires with a small screwdriver. 4. Check all other wiring and connectors for bent pins or mis-wires. If the chatter does not stop, the electromechanical relay or contactor is probably defective.

  • Page 93: Unit Maintenance

    No maintenance is ordinarily required except the routine removal of dirt and debris from the outside surface of the fins. McQuay recommends the use of foaming coil cleaners available at most air conditioning supply outlets. Use caution when applying such cleaners as they may contain potentially harmful chemicals.

  • Page 94: Preventative Maintenance Schedule

    clogged filter-drier or a restriction elsewhere in the liquid line See Table 54 for maximum allowable pressure drops. If subcooling is low add charge to clear the sightglass. If subcooling is normal (10°- 15°F) and flashing is visible in the sightglass check the pressure drop across the filter-drier. Subcooling should be checked at full load with 70°F (21.1°C) outdoor air temperature and all fans running.

  • Page 95: Unit Service

    Unit Service CAUTION 1. Service on this equipment is to be performed by qualified refrigeration personnel familiar with equipment operation, maintenance, correct servicing procedures, and the safety hazards inherent in this work. Causes for repeated tripping of safety controls must be investigated and corrected. 2.

  • Page 96: Evaporator

    Evaporator The evaporator is the direct expansion, shell-and-tube type with refrigerant flowing through the tubes and water flowing through the shell over the tubes. The tubes are internally finned to provide extended surface as well as turbulent flow of refrigeration through the tubes. Normally no service work is required on the evaporator.
  • Page 97 3. The charge can be added at any load condition between 25-100% load per circuit but at least two fans should be operating per refrigerant circuit if possible. The suction superheat should be in the 6°F-12°F (3.3°C-6.6°C) range. 4. Add sufficient charge to clear the liquid line sightglass and until all flashing stops in the sightglass. Add an extra 15-20 lbs.

  • Page 98: Agr Troubleshooting Chart

    AGR Troubleshooting Chart PROBLEM POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS Main Switch. Close Switch. Fuse Blown. Circuit breakers open Check electrical circuits and motor windings for shorts or grounds. Investigate for possible overloading. Replace fuse or reset breakers after fault is corrected. Check for loose or corroded connections.

  • Page 99: Notes

    Notes IOMM AGR-1 AGR 070A through 100A...
  • Page 100 Post Office Box 2510, Staunton, Virginia 24402 USA • (800) 432-1342 • www.mcquay.com...

This manual is also suitable for:

Agr 075asAgr 085asAgr 095as

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