Table of Contents
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Installation & Operation Manual
10EER 7.5 & 10 Ton Vertical Wall Mount
Air Conditioners
Installation & Operation Manual
10 EER Vertical Wall-Mount Air Conditioners
MODELS:
MGA3090A & MGA3120A
(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 Division of the AIRXCEL
Commercial Group
®
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 MGA3090-3210 Wall Mount AC I&O Manual 03/2021 Rev.6
Part #03836
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Table of Contents
Troubleshooting
Related Manuals for Airxcel Marvair MGA3090A
Summary of Contents for Airxcel Marvair MGA3090A
- 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 Division of the AIRXCEL Commercial Group ® P.O. Box 400 • Cordele, Georgia 31010 • 156 Seedling Drive • Cordele, Georgia 31015 (229) 273-3636 •...
- 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. © 03/2021 Marvair Div. Airxcel , Inc. ® ™ Marvair MGA3090-3120 I&O Manual 03/2021 Rev.6...
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Page 3: Table Of Contents
WARNING • If the information in these instructions are not followed exactly, a fire may result causing property damage, personal injury or loss of life. • Read all instructions carefully prior to beginning the installation. Do not begin installation if you do not understand any of the instructions. •... - Page 4 Table of Contents Chapter 5 Troubleshooting Overview ..............................36 Failure Symptoms Guide ........................37 Compressor Troubleshooting .........................37 Chapter 6 Maintenance Scheduled Maintenance .........................39 Chapter 7 Warranty Limited Product Warranty ........................40 Chapter 8 Start-Up Check List Start-Up Check List ..........................41 Illustrations Figure 1. PLC ............................10 Figure 2.
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Page 5: General Description
Chapter 1 Description & Specifications General Description The Marvair MGA3090A & MGA3120A 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 90,000-120,000 BTUH. -
Page 6: Model Identification
Model Identification The model identification number is found on the data sticker. Rating plate located on side panel. Example Position Unit Designation/Family M = Marvair Wall Mount D = Dry Bulb Sensor Indoor Air Quality E = Dry Bulb Sensor w/Dirty Filter Energy Efficiency Ratio (EER) G = 10 Features G = Dirty Filter Sensor... -
Page 7: Table 1 Efficiency And Capacity Ratings At Ansi/Ahri Standard 390
Note: Follow local codes and standards when designing duct runs to deliver the required airflow. Minimize noise and excessive pressure drops caused by duct aspect ratio changes, bends, dampers and outlet grilles in duct runs. Basic Model Cooling BTUH Rated Air Flow (CFM) MGA3090A 89,000 3,500... -
Page 8: Table 4 Single Compressor Cooling Performance (Btuh) At Various Outdoor Temperatures
Outdoor Temperature Basic Model 75ºF / 24ºC 80ºF / 26.5ºC 85ºF / 29ºC 90ºF / 32ºC 95ºF / 35ºC MGA3090A 46,980 45,360 43,740 42,120 40,500 MGA3120A 69,286 66,896 64,507 62,118 59,729 Based upon ANSI/AHRI std. 390 return air conditions of 80°F DB/67° WB (26.5°C DB/19.5°C WB) at various outdoor temperatures. Table 4. -
Page 9: General Operation
General Operation Hot Gas By-Pass Normally used in specialty applications (i.e Magnetic Resonance Imaging (MRI) buildings) to prevent magnetic voltage disturbance caused by cycling. This technology is applied in this product to extend the operation envelope for the compressor to 20º F (-6.6ºC). Combined with a condenser low ambient Fan Cycle feature, compressor operation can be extended to 0º... -
Page 10: Figure 1. Plc
Figure 1. Programmable Logic Controller PLC Inputs & Outputs The PLC has inputs located along the top right of the controller and outputs along the bottom right of the controller. An input is a signal to the PLC from either the thermostat, sensors in the air conditioner, or a customer supplied input, e.g., EMS (Energy Management System). -
Page 11: 1.7 Unit Operation
• LOI – Lock Out Indicator. A blinking LED indicates that a pressure switch has opened or a motor fault has occured. Refer to section 1.8 for additional information concerning this indicator. • FR – Fault Relay. An isolated form C relay contact is provided for the customer’s use to monitor for fault conditions with the HPS or LPS switches. - Page 12 PLC External LED Indicator Lights Type LED Indicator Color Description Green PLC is in run mode RUN/STOP Yel- PLC is in stop mode Power ERROR PLC has encountered an error Yel- Maintanence is required MAINT DI a .0 Green High Pressure Switch A DI a .1 Green Low Pressure Switch A DI a .2...
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Page 13: Optional Controls And Packages
1.8 Optional Controls & Packages Protective Coating Packages Two corrosion protection packages are offered- one for the condenser section (the Coastal Environmental package) and the other for the entire unit (the Coat-All Package). The condenser protection package includes: • Corrosion resistant fasteners •... -
Page 14: Figure 2. Typical Electrical Schematic
Figure 2. Typical Electrical Schematic Marvair MGA3090-3120 I&O Manual 03/2021 Rev.6... -
Page 15: Chapter 2 Electronic Control Board
Chapter 2 Electronic Control Board Introduction WARNING Failure to observe the instructions contained in this document may result in personal injury and/or property damage and may void the warranty. Read this manual before installing, replacing or using this product. The MGA3090 is equipped with Marvair’s proprietary Printed Circuit Board (PCB), which sets the standard for the industry in flexibility, reliability and performance. -
Page 16: Installation And Replacement
Item Description Outdoor Motor Control Signal Output Indoor Motor Control Signal Output P 1/2- Pressure for Circuit 1 and Circuit 2 (Respectively) FS1 – Freeze Stat for Circuit 1 FS2 – Indoor Temperature Input Modbus Communication 3 Wire [A, B, COM] and Parallel RJ-11 Port Fan Cycle Control Input (only Applicable for EC Outdoor Motors) Hum –... -
Page 17: Figure 3A. Setting The Speed For The Y1 And Y2 Operation For Indoor Motor
Power The Marvair PCB requires 24 VAC to operate. When the board is sufficiently powered, the “PWR” status light on the PCB illuminates “Green.” If there is insufficient power to the board, the “STATUS 1” and “STATUS 2” flashes continuously. Insufficient power to the board will result in no outputs being energized. -
Page 18: Figure 4. Output Termination For Indoor Motor Control Signal
Output Termination for Indoor Motor Control Signal Note: Follow data (wiring and signal control signal type) of the appropriate motor to setup the PCB Indoor Motor PWM Signal Output. Reference Wire Connected to “GND” and the Signal Connected to “PWM” Indoor Motor 0-10V Signal Output. -
Page 19: Figure 7. Communications Setup
Communication The Marvair PCB comes equipped with MODBUS communication standard. There are 2 adjacent MODBUS communication ports connected in parallel. That is, both ports transmit the same information. The difference between the ports is the physical connection. One port is for RS-485 (3 wire shielded cable is recommended) and the other port is RJ-11. -
Page 20: Sequence Of Operation
Address DIP Switch 1 DIP Switch 2 DIP Switch 3 DIP Switch 4 0 [Local Control] Table 9. MODBUS Network Address DIP Swith Positions Sequence of Operation IMPORTANT All equipment should go through the recommended commissioning/start up sequence to ensure safety and system reliability. This document is only valid if the system is used as intended. - Page 21 Equipment, devices and necessary system components are specified in the respective section. Note: 1. All inputs on the Controller go through a 5 seconds Time-On Delay to prevent nuisance request. Compressor Outputs go through 5 seconds staggered Time On delay to prevent nuisance tripping of breaker due to the inrush associated with these large inductive loads.
- Page 22 and the indoor fan remains on continuously but the outdoor fan cycles based on head pressure. The Fan Cycle Control Switch (Low Ambient Control Switch) closes at 400 PSIG to set the “FCC IN” input High which in turn outputs a speed proportional to the “OFM Speed” setting on the board or by MODBUS.
- Page 23 5.0 – Refrigeration Protection 5.1– High Pressure Lockout This condition describes the abnormal rise in Head Pressure pass the system acceptable limit of 660 PSI (+/-20PSI). The fault will only be active when the High-Pressure Switch (Normally Closed) opens during a request for Cooling. The first time this fault condition occurs, the system cuts the compressor off WITHOUT locking out.
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Page 24: Table 10A. Modbus Discrete Registers
5.2 – Modulating Head Pressure Control A 10K Nominal NTC Thermistor is connected to the “P1” and “P2” inputs for circuit 1 and circuit 2 respectively. When this sensor is connected, the “FCC IN” is ignored and the thermistor value is used as the process variable when controlling the head pressure. -
Page 25: Table 10B. Modbus Registers
Registers: Read with Function Code 04, Write to RW or WO registers with Function Code 06 Description Size Data Format Heat Setpoint 16 Bit 45º-100º F Cool Setpoint 16 Bit 45º-100º F 0-20, 10 is default. Less Temperature Calibration 16 Bit than 10 is a negative offset, 11-20 is a positive offset 0-100, 80 is default. -
Page 26: Chapter 3 Installation
Chapter 3 Installation WARNING Failure to observe and follow Warnings and Cautions and these Instructions could result in death, bodily injury or property damage. Read this manual and follow its instructions and adhere to all Cautions and Warnings in the manual and on the unit. Equipment Inspection Concealed Damage Inspect all cartons and packages upon receipt for damage in transit Remove cartons and check for... -
Page 27: Installation Materials
Duct work should be designed and installed in accordance with all applicable safety codes and standards. Marvair strongly recommends referring to the current edition of the National Fire Pro- tection Association Standards 90A and 90B before designing and installing duct work. The duct system must be engineered to insure sufficient air flow through the unit to prevent over-heating of the heater element. - Page 28 Kit Components: Accessories: The package may include other factory-supplied items (optional): Description K/10439 CommStat Touch Controller, Solid State Lead/Lag Controller w/Touch Screen S/07846 CommStat 4 Controllers, Solid State Lead/Lag Controller 50123 Digital thermostat. 1 stage heat, 1 stage cool. 7 day programmable. Fan switch: Auto & On.
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Page 29: Porting And Duct Work
Porting and Duct Work General Information Note: The following instructions are for general guidance only. Due to the wide variety of installation possibilities, specific instructions will not be given. When in doubt, follow standard and accepted installation practices, or contact Marvair for additional assistance. -
Page 30: Installing The Lifting Brackets
Figure 8. Top Flange and Lifting Bracket Installation (Typical) Installing the Optional Lifting Brackets Lifting brackets are available which can be installed on the top of the side panels. These brackets allow the unit to be picked up using lifting eyes in the brackets. Attach the brackets to the left and right side panels as shown in Figure 3. -
Page 31: Electrical Connections
For units with electric heat, a one inch clearance is required around the duct extensions. The duct extensions must be constructed of galvanized steel with a minimum thickness of .019” as per the NFPA standards 90A & 90B. Figure 9. Air Conditioner Wall Mount Detail Electrical Connections WARNING ELECTRICAL SHOCK HAZARD Failure to follow safety warnings exactly could result in serious injury, death, and/or... - Page 32 the installation of gauges may be objectionable, can be made by monitoring the temperature of the refrigerant lines at the compressor. The temperature should rise on the discharge line while the suction line temperature decreases. Reverse rotation also results in a substantially reduced current draw when compared to tabulated values.
- Page 33 Dual Unit Phasing For applications where one controller operates two units, e.g., the CommStat 4. 1. Wire each unit as described in steps 1 through 4 above. 2. Test for proper phasing as follows: A. Power up the units. B. Using an AC volt meter set to the 300 volt scale, measure voltage between terminal L1 on the compressor contactor of unit #1 and terminal L1 on the compressor contactor of unit #2 If voltage is present, units are wired out of phase and must be rewired.
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Page 34: Figure 10A. Thermostat Connection Diagram
Figure 10a. Thermostat Connection Diagram Figure 10b. CommStat 3 Wiring Diagram Marvair MGA3090-3120 I&O Manual 03/2021 Rev.6... -
Page 35: Chapter 4 Start-Up
Chapter 4 Start-Up Check-Out of Cooling Cycle Important: Be sure that the crankcase heater (if used) has been energized for at least 24 hours before starting the unit(s). Double-check all electrical connections before applying power. All air conditioners with scroll compressors running on 3Ø power must be checked for proper rotation during the initial start-up. -
Page 36: Chapter 5 Troubleshooting
Chapter 5 Troubleshooting Overview The middle front panel provides access to the electrical/control box and to the filters. This panel has hinges on the left and right hand side. This panel should ONLY be opened by using the two hinges on the left side OR the two hinges on the right side. -
Page 37: Failure Symptoms Guide
Failure Symptoms Guide PROBLEM/SYMPTOM LIKELY CAUSE(S) CORRECTION A. Unit does not run. 1. Power supply problem. 1. Check power supply for adequate phase and voltage. Check wiring to unit and external breakers or fuses. NOTE: An internal anti-short-cycle 2. Tripped internal disconnect. 2. - Page 38 1. Start-Up Voltage: Measure the voltage at the compressor contactor during start-up. The voltage must exceed the minimum shown in Table 5, section 2.2, or compressor failure is likely. A low voltage condition must be corrected. 2. Running Amperage: Connect a clip-on type ammeter to the (common) lead to the compressor. Turn on the supply voltage and energize the unit.
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Page 39: Chapter 6 Maintenance
Chapter 6 Maintenance The middle front panel provides access to the electrical/control box and to the filters. This panel has hinges on the left and right hand side. This panel should ONLY be opened by using the two hinges on the left side OR the two hinges on the right side. -
Page 40: Chapter 7 Warranty
Chapter 7 Warranty Marvair, Inc. Limited Product Warranty Marvair Inc., warrants its products to be free from defects in materials and workmanship under normal use to the original purchaser for the period of time in the table below. If any part of your product fails within 12 months from start-up, or 18 months from shipment from the factory, whichever comes first, Marvair, Inc. -
Page 41: Start-Up Check List
Chapter 8 Start-Up Check List The middle front panel provides access to the electrical/control box and to the filters. This panel has hinges on the left and right hand side. This panel should ONLY be opened by using the two hinges on the left side OR the two hinges on the right side. - Page 42 Condensate Section Has water been placed in drain pan to confirm proper drainage? ❒Yes ❒No Are correct filters in place? ❒Yes ❒No Refrigerant Piping If leaks are found, report any leaks to Marvair Warranty Service Dept. C. Check Rated Voltage at Terminal Block for Imbalance before starting of Unit. ❒208/230V 1 Phase ❒208/230V 3 Phase ❒460V 3 Phase...
- Page 43 D. Heating Mode Check & Record Readings Circuit 1 Circuit 2 (if applicable) Room Temperature ________ ________ Outside Temperature ________ ________ Evap. Entering Air DB Temp ________ ________ Evap. Entering Air WB Temp ________ ________ Evap. Leaving Air DB Temp ________ ________ Evap.
- Page 44 After 10 minutes of compressor operation, record the following: Circuit 1 Circuit 2 (if applicable) Room Temperature ________ ________ Outside Temperature ________ ________ Suction Pressure ________ ________ Suction Line Temperature ________ ________ Discharge Pressure ________ ________ Discharge Line Temperature ________ ________ Entering Condenser Air ________...
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