ACS Marvair MGA3090A Installation & Operation Manual
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ACS Marvair MGA3090A Installation & Operation Manual

10eer 7.5, 10 & 12.5 ton vertical wall mount air conditioners
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Installation & Operation Manual
10EER 7.5, 10 & 12.5 Ton Vertical Wall Mount
Air Conditioners
Installation & Operation Manual
10 EER Vertical Wall-Mount Air Conditioners
MODELS:
MGA3090A, MGA3120A & MGA3150A
(Dual Compressor)
IMPORTANT
This manual may include information for options and features which may not be
included on the unit being installed. Refer to the unit data label or Model Identification
to determine which features and options this unit is equipped with.
INSTALLER: Affix the instructions on the inside of the building adjacent to the thermostat.
END USER: Retain this manual for future reference.
Manufactured By:
Marvair, An ACS Brand
P.O. Box 400 • Cordele, Georgia 31010 • 156 Seedling Drive • Cordele, Georgia 31015
(229) 273-3636 • Fax (229) 273-5154
www.Marvair.com
The most current version of this manual can be found at www.Marvair.com.
Marvair MGA3090-3150 Wall Mount AC I&O Manual 08/2022 Rev.12
Part #03836

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  • Page 1 INSTALLER: Affix the instructions on the inside of the building adjacent to the thermostat. END USER: Retain this manual for future reference. Manufactured By: Marvair, An ACS Brand P.O. Box 400 • Cordele, Georgia 31010 • 156 Seedling Drive • Cordele, Georgia 31015 (229) 273-3636 • Fax (229) 273-5154 www.Marvair.com...
  • Page 2 Failure to comply could result in minor personal injury and/or property damage. CAUTION Used to point out helpful info that will result in improved installation, reliability or operation. IMPORTANT SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE. © 06/2022 Marvair, An ACS Brand Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 3: Table Of Contents

    Porting and Duct Work ..........................29 Top Flange Installation ..........................29 Installing the Lifting Brackets ........................30 Mounting the Unit ..........................30 Electrical Connections ...........................31 Chapter 4 Start-Up Check-Out of Cooling Cycle .........................35 Check-Out of Heating Cycle ........................35 Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 4 Table 9 MODBUS Network Address DIP Swith Positions ..............20 Table 10a. MODBUS Discrete Registers ...................... 24 Table 10b. MODBUS Registers........................25 Table 11 Minimum Clearances ........................27 Table 12 Voltage Limitations ........................27 Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 5: General Description

    Chapter 1 Description & Specifications General Description The Marvair MGA3090A, MGA3120A & MGA3150A are a series of vertical wall-mounted air conditioning systems that provide heating, cooling, and ventilation for telecommunication shelters, and other applications with high internal heat gains. The series is available in nominal cooling capacities of 90,000-150,000 BTUH.

  • Page 6: Model Identification

    11 = November 23 = 2023 04 = April 08 = August 12 = December Capacities, Weights and Filter Sizes See the Product Data Sheet for complete electrical and performance specifications and dimensional drawings. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 7: Table 1 Efficiency And Capacity Ratings At Ansi/Ahri Standard 390

    90,635 87,494 84,427 81,286 78,146 75,005 71,865 68,798 67,191 65,876 64,562 63,247 84/71 (29/22) Sensible 83,360 82,358 81,383 80,389 78,146 75,005 71,865 68,798 67,191 65,876 64,562 63,247 Table 3. Single Compressor Cooling Performance (BTUH) at Various Outdoor Temperatures Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 8: Table 4 Dual Compressor Cooling Performance (Btuh) At Various Outdoor Temperatures

    1,294 2,489 1,422 1,219 MGA3150A Reverse Flow 1,212 1,294 2,489 1,422 1,219 MGA3150A w/Economizer 1,262 1,348 2,489 1,422 1,219 MGA3150A Reverse Flow w/Economizer 1,262 1,348 2,489 1,422 1,219 Table 6. Shipping Weights & Dimensions Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 9: General Operation

    1 of the low voltage terminal strip and the 2nd stage cooling input is terminal 2 of the low voltage terminal strip. The thermostat must be programmed for 2 stage cooling operation when 2 stage compressor operation is desired. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 10: Programmable Logic Controller (Plc)

    PLC to the air conditioner, to the thermostat or to the customer. PLC Inputs The PLC inputs are powered by 24 VDC. The inputs are: • Y – Compressor • Y2 – Dual Compressor Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 11 The PLC has indicator LED’s that show the status of all thermostat inputs and outputs. For example, if the “G” LED is on, this means that voltage is present from the “G” terminal on the thermostat. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 12: 1.7 Unit Operation

    Emergencey Management System fault • Delay on Make – On initial power up or on resumption of power, the air conditioner will wait 3 minutes from a call for cooling before allowing the contactor to energize. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 13: Optional Controls And Packages

    Power must be applied to the unit for 24 hours before starting the compressor. The condenser (outside fan) motor is energized by the same contactor. The indoor evaporator fan motor is controlled by the fan purge on the electronic control board. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 14: Figure 2. Typical Electrical Schematic

    Figure 2. Typical Electrical Schematic Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 15: Chapter 2 Electronic Control Board

    MODBUS. This chapter provides the necessary information for installing and operating the Marvair PCB. The diagram below identifies the inputs, outputs and connections for the Marvair PCB. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 16: Installation And Replacement

    Low pressure switch has opened twice Status 2 3 Blinks Freeze stat (optional) - Indoor coil temperature is below 35°F (1°C) Continuous Flash of Both LEDs Insufficient voltage to the board. Less than 20 Volts Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 17: Figure 3A. Setting The Speed For The Y1 And Y2 Operation For Indoor Motor

    To set second stage cooling (Y2 request) speed, put Bridge Jumper on the “Y2 pin and center pin” shown in the figure below. Use the potentiometer marked “IBM SPEED” to set the required speed. Bridge Jumper Position For Setting Y2 Speed IBM SPEED Potentiometer Figure 3b. Second Stage Cooling Speed Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 18: Figure 4. Output Termination For Indoor Motor Control Signal

    Outdoor Motor PWM Signal Output. One Wire Connected to “GND” and the Other Connected to “PWM” Outdoor Motor 0-10V Signal Output. One Wire Connected to “GND” and the Other Connected to “0-10V” Figure 6. Output Termination for Outdoor Motor Control Signal Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 19: Figure 7. Communications Setup

    RS-485 Termination MODBUS Network Address DIP switches. See Addressing Table Baud Rate - 19200 BPS: Between Upper and Middle Pin Baud Rate - 9600 BPS: Between Lower and Middle Pin Figure 7. Communications SetUp Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 20: Sequence Of Operation

    5.0 Refrigeration Protection 5.1 High Pressure Lockout 5.2 Low Pressure Lockout 5.3 Low Voltage 5.4 Anti-short Cycle 6.0 Additional Features 6.1 MODBUS communication 6.2 Modulating Head Pressure Control 6.3 Freeze Stat Operation 6.4 Onboard Thermostat Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 21 Indoor Fan Motor, that is proportional to the “Y1” speed setting on the board or via MODBUS. It also outputs a request dependent (based on FCC IN) control signal for the Outdoor Fan Motor. In Stage 1 Cooling operation, the compressor Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 22 (based on “FCC IN” Input) and outputs a signal proportional to board or MODBUS setting when the “FCC IN” input is High. The board continues to produce these outputs until the Dehumidification request is dropped. Once this request is dropped, the Indoor Fan Motor continues to run for 90 seconds. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 23 The sequence of operation is the same as described above for the various operation, but Indoor Motor speeds for various operation, Outdoor Motor Speed, Heating Setpoint and Cooling Setpoint (if applicable) has to be configured via MODBUS. See MODBUS register tables at the end of this section. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 24: Table 10A. Modbus Discrete Registers

    0 = Off, 1 = Energized 0 = Modbus only Enables or disables reading the thermostat inputs in Modbus 1 Bit 1 = Read thermostat Inputs mode Default is 0 Table 10a. MODBUS Discrete Registers Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 25: Table 10B. Modbus Registers

    11 = Future Use 12 = Future Use 13 = Freeze Fault 1 14 = Freeze Fault 2 15 = Y1 Locked Out 16 = Y2 Locked Out 17 = Low Voltage Table 10b. MODBUS Registers Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 26: Chapter 3 Installation

    D) When installing multiple units, please note the recommended clearances noted in Table 4. 4. Airflow Requirements: Maximum Static Pressures MGA3090A MGA3120A MGA3150A Keep duct lengths as short as possible. Do not obstruct airflow through the unit. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 27: Installation Materials

    Before installing the unit, remove the bracket and reattach as described in Section 2.5 The Lifting brackets are shipped attached to the back panel of the unit. These brackets provide a method for lifting it. The installation of the brackets is described in Section 2.6. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 28 The information contained in this manual is intended for use by a qualified service agency that is experienced in such work, is familiar with all precautions and safety procedures required in such work, and is equipped with the proper tools and test instruments. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 29: Porting And Duct Work

    Remove the 4 screws in these holes and use these screws to attach the top flange to the air conditioner. 3. Apply a bead of silicone sealer on the wall side of the bottom support brackets on the unit. Circle the mounting holes with the silicone bead. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 30: Installing The Lifting Brackets

    7. Check the fit of each sleeve to its mating flange for possible air leaks. Apply silicone sealer to close any gaps. Install the air return and supply grilles. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 31: Electrical Connections

    Verification of proper rotation is made by observing that the suction pressure drops and the discharge pressure rises when the compressor is energized. An alternate method of verification for self contained system with small critical refrigerant charges, where Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 32 Insulate the orange lead. CAUTION The external breaker(s) that provide power to the air conditioner must be sized per the maximum Fuse Size (MFS) shown on the Unit's data label. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 33 Continuous fan operation: For continuous indoor fan operation on single units, install a jumper between terminals 8 and 3. CommStat 4 Lead /Lag Controller Please refer to the Product Data sheet for the CommStat 4 controller for complete instructions on installing and programming this controller. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 34: Figure 10A. Thermostat Connection Diagram

    Figure 10a. Thermostat Connection Diagram Figure 10b. CommStat 3 Wiring Diagram Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 35: Chapter 4 Start-Up

    1. Raise the heating set point temperature to a setting which is higher than the ambient temperature. The fan and electric heat should immediately cycle on. 2. Move the system switch to the "OFF" position. All functions should stop. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 36: Chapter 5 Troubleshooting

    Use refrigeration goggles when servicing the refrigeration circuit. WARNING The refrigerant circuit has hot surfaces, and the electrical voltages inside of the unit may be hazardous or lethal. SERVICE MAY BE PERFORMED ONLY BY QUALIFIED AND EXPERIENCED PERSONS. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 37: Failure Symptoms Guide

    3. Defective heater contactor. 3. Check relay for proper operation. Replace if defective. Compressor Troubleshooting NOTE: It is important to rule out other component failures before condemning the compressor. The following electrical tests will aid diagnosis: Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 38 A short circuit at high voltages indicates a motor defect. Do not do this test under vacuum. 5. On single phase models, check the capacitor by substitution. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 39: Chapter 6 Maintenance

    Some solvents can cause the drain pan to corrode. Lubrication The condenser fan motor(s) and the evaporator blower motor(s) never require oiling. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 40: Chapter 7 Warranty

    THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, AND YOU MAY ALSO HAVE OTHER RIGHTS WHICH VARY FROM STATE-TO- STATE. Some states do not allow limitations or exclusions, so the above limitations and exclusions may not apply to you. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 41: Start-Up Check List

    Are all wiring terminals (including main power supply) tight? ❒Yes ❒No If unit has a crankcase heater, has it been energized for 24 hours? ❒Yes ❒No On a 208/230 v. units is control transformer (24 AC) wired for correct voltage? ❒Yes ❒No Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 42 L1 & L3 = 243 Volts = 717 / 3 = 239 Average Voltage L2 & L3 = 233 Volts 239 - 233 = 6 100 x 6/239 =2.5% Voltage Unbalance Three phase units only check fan & compressor rotation. Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 43 Measured Line to Line Volts L1&L2_______V. L1&L3 ________V. L2&L3______V. (L1&L2 + L1&L3 + L2&L3)/3 = Avg. Voltage = _______________ Max. Deviation from avg. voltage = ______________volts Voltage imbalance = (100 x Max. Deviation)/avg. Voltage = ___________% Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 44 Evap. Leaving Air WB Temp ________ ________ Compressor Amps (L1) ________ ________ Compressor Amps (L2) ________ ________ Compressor Amps (L3) ________ ________ Notes: _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

  • Page 45: Fresh Air Damper Installation

    Appendix A Fresh Air Damper Installation Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...
  • Page 46 15% of rated air flow of fresh air, in 5% increments. The hood is shipped from the factory in the closed position (no fresh air). To provide fresh air, remove the two screws on either side of the hood and reposition as desired. Fresh Air Hood Damper Marvair MGA3090A-3150A I&O Manual 08/2022 Rev.12...

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Marvair mga3120aMarvair mga3150a

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