ACS Marvair MAA1018A-MAA1060A User manual

MODELS:
MAA1018A-MAA1060A, MGA1072A
(Single Stage)
MAA2060A-MAA2072A, MGA2072A
(2-Stage)
Installation & Operation Manual
10 & 11 EER Vertical Wall-Mount Air Conditioners
Manufactured By:
Marvair, An AirX Climate Solutions Brand
P.O. Box 400 • Cordele, Georgia 31010 • 156 Seedling Drive • Cordele, Georgia 31015
[phone] • Fax [phone]
E-mail: [e-mail] • Internet: www.Marvair.com
The most current version of this manual can be found at www.Marvair.com.
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 Identication
to determine which features and options this unit is equipped with.
INSTALLER: Afx the instructions on the inside of the building adjacent to the thermostat.
END USER: Retain this manual for future reference.
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
Air Conditioner Product Manual
Vertical Wall-Mount Air Conditioners
with Front Control Box Panel

2
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
How To Use This Manual
This manual is intended to be a guide to the Marvair Wall Mount family of vertical air conditioners. It contains installation,
troubleshooting, maintenance, warranty, and application information. The information contained in this manual is to be
used by the installer as a guide only. This manual does not supersede or circumvent any applicable national or local codes.
If you are installing the Marvair unit, rst read Chapter 1 and scan the entire manual before beginning the installation as
described in Chapter 2. Chapter 1 contains general, descriptive information and provides an overview which can speed
up the installation process and simplify troubleshooting.
If a malfunction occurs, follow this troubleshooting sequence:
1. Make sure you understand how the Marvair unit works (Chapters 1 & 3).
2. Identify and correct installation errors (Chapter 2).
3. Refer to the troubleshooting information in Chapter 4.
If you are still unable to correct the problem, contact the Factory at 1-800-841-7854 for additional assistance.
Please read the following “Important Safety Precautions” before beginning any work.
Important Safety Precautions
1. USE CARE when LIFTING or TRANSPORTING equipment.
2. TRANSPORT the UNIT UPRIGHT. Laying it down on its side may cause oil to leave the compressor and breakage
or damage to other components.
3. TURN ELECTRICAL POWER OFF AT THE breaker or fuse box BEFORE installing or working on the equipment.
LINE VOLTAGES ARE HAZARDOUS or LETHAL.
4. OBSERVE and COMPLY with ALL applicable PLUMBING, ELECTRICAL, and BUILDING CODES and ordinances.
5. SERVICE may be performed ONLY by QUALIFIED and EXPERIENCED PERSONS.
* Wear safety goggles when servicing the refrigeration circuit
* Beware of hot surfaces on refrigerant circuit components
* Beware of sharp edges on sheet metal components
* Use care when recovering or adding refrigerant
6. Use COMMON SENSE - BE SAFETY-CONSCIOUS
This is the safety alert symbol . When you see this symbol on the Marvair unit and in the instruction manuals
be alert to the potential for personal injury. Understand the signal word DANGER, WARNING, CAUTION and
IMPORTANT. These words are used to identify levels of the seriousness of the hazard.
DANGER Failure to comply will result in death or severe personal injury and/or property damage.
WARNING Failure to comply could result in death or severe personal injury and/or property damage.
CAUTION Failure to comply could result in minor personal injury and/or property damage.
IMPORTANT Used to point out helpful suggestions that will result in improved installation, reliability or
operation.
© 06/2023 Marvair, An AirX Climate Solutions Brand
AS PART OF THE MARVAIR CONTINUOUS IMPROVEMENT PROGRAM, SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE.

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
3
WARNING
• If the information in these instructions are not followed exactly, a re 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.
• Improper installation, adjustment, alteration, service or maintenance can cause property
damage, personal injury or loss of life.
• Installation and service must be performed by a qualied installer or service agency in
accordance with these instructions and in compliance with all codes and requirements
of authorities having jurisdiction.
INSTALLER: Afx the instructions on the inside of the building adjacent to the
thermostat.
END USER: Retain these instructions for future reference.
Table of Contents
Chapter 1 Marvair Wall Mount Air Conditioner Description & Specications
1.1 General Description .................................................................................................................................5
1.2 Model Identication .................................................................................................................................6
1.3 Serial Number Date Code ........................................................................................................................7
1.4 Air Flow, Weights and Filter Sizes...........................................................................................................7
1.5 General Operation ....................................................................................................................................7
1.6 Optional Controls and Packages ..............................................................................................................8
1.7 Electrical Operation ...............................................................................................................................11
Chapter 2 Electronic Control Board
2.1 Introduction ............................................................................................................................................17
2.2 Installation and Replacement .................................................................................................................18
2.3 PCB Details and Information .................................................................................................................18
2.4 Operation................................................................................................................................................22
2.5 Sequence of Operation ...........................................................................................................................22
Chapter 3 Installation
3.1 Equipment Inspection.............................................................................................................................34
3.2 Installation Requirements.......................................................................................................................34
3.3 Installation Materials .............................................................................................................................36
3.4 Porting and Duct Work ..........................................................................................................................37
3.5 Fresh Air Hood Installation ...................................................................................................................38
3.6 Bracket Installation ...............................................................................................................................39
3.7 Mounting the Unit .................................................................................................................................39
3.8 Electrical Connections ...........................................................................................................................40
Chapter 4 Start-Up
4.1 Check-Out of Cooling Cycle .................................................................................................................44
4.2 Check-Out of Heating Cycle..................................................................................................................44

4
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
Chapter 5 Troubleshooting
5.1 Overview ................................................................................................................................................45
5.2 Failure Symptoms Guide........................................................................................................................45
5.3 Compressor Troubleshooting .................................................................................................................46
5.4 Control Board Diagnosis........................................................................................................................47
Chapter 6 Maintenance
6.1 Scheduled Maintenance .........................................................................................................................48
Chapter 7 Warranty
7.1 Marvair Limited Product Warranty ........................................................................................................49
Chapter 8 Start-Up Checklist
8.1 Start-Up & Commissioning Form..........................................................................................................50
Appendix A
Installation Instructions for Field Installed Electric Heaters ...........................................................................54
Illustrations
Figure 1a. Typical Electrical Schematic - Model MAA..............................................................................12
Figure 1b. Typical Electrical Schematic - Model MAA with Economizer..................................................13
Figure 1c. Typical Electrical Schematic - Model MAA (Alternate Construction with Economizer) ........14
Figure 1d. Typical Electrical Schematic - Model MAA (Alternate Construction with Economizer) .........15
Figure 1e. Typical Electrical Schematic - Model MAA (Alternate Construction with Economizer) .........16
Figure 2. Enthalpy Sensor and Temperature Control Points .....................................................................27
Figure 3. Dry Bulb sensor..........................................................................................................................28
Figure 4. Fresh Air Hood Damper, Models 1024A-1072A .......................................................................38
Figure 5. Wall Mounting Detail.................................................................................................................39
Figure 6a. Humidistat Wiring Details to a Marvair Air Conditioner with Reheat ......................................42
Figure 6b. Thermostat Connection Diagram ...............................................................................................42
Figure 6c. CommStat™ 4 HVAC Controller Wiring Detail........................................................................42
Tables
Table 1 CFM @ External Static Pressure .................................................................................................7
Table 2 Return Air Filter Sizes .................................................................................................................7
Table 3 Installed Unit Weights..................................................................................................................7
Table 4 Ambient Temperature Operating Range ......................................................................................7
Table 5 Refrigerant Charge.......................................................................................................................8
Table 6. Modbus Network Address DIP Switch Positions ......................................................................26
Table 7 Minimum Clearances.................................................................................................................35
Table 8 Voltage Limitations....................................................................................................................35
Table 9 Maximum Static Pressure ..........................................................................................................38

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
5
Chapter 1 Description & Specications
1.1 General Description
The Marvair MAA and MGA are a series of vertical wall-mounted air conditioning systems that provide
heating, cooling, and ventilation for electronic equipment shelters, process control centers, and other
applications with high internal heat gains. The series includes multiple sizes and nominal cooling
capacities from 18,000 to 72,000 BTUH. Resistance heating elements are available in various wattages.
MAA modes are available with cooling capacities of 18,000 to 60,000 BTUH and EER’s of 11.00 to
11.50. MGA models have 72,000 BTUH (6 ton) capacity and are 10 EER. The Marvair Product Data
Sheets have detailed information on the capacities and efciencies for each model.
See Appendix A for instructions on eld installation of electric heat.
Marvair air conditioners feature an exclusive electronic control board. The control board consolidates
several of the electrical components and improves the air conditioner’s reliability. The control board
replaces the blower relay, the lockout relay, the compressor time delay and the timed low pressure
bypass. In addition, the control board has LED’s to indicate operating status and fault conditions to
assist the service technician. A complete description of functions of the control board is in Chapter 2.
All models are designed for easy installation and service. Major components are accessible for service
beneath external panels.
All units have internal disconnects (optional on 380V and 575V). Follow local codes for external
disconnect requirements.
Marvair wall mount air conditioners have a 0-15% manual outside air damper as standard equipment.
All models are available with an optional factory installed economizer for 100% free cooling with
outside air.

6
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
1.2 Model Identication
The model identication number is found on the data sticker. Rating plate located on side panel.
Example M A A 1 0 3 6 A D 0 5 0 C + + + + 1 E A + A 3 1 + + + + + +
Position 1234567891011 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
1Unit Designation/Family M = Marvair Wall Mount
S = Stock Unit
2Energy Efciency Ratio
(EER)
A = 11
G = 10
3Refrigerant Type A = R-410a
4Compressor Type/Quantity 1 = Fixed Speed/Single
2 = 2-Stage/Single
5
Unit Capacity/Nominal
Cooling (BTUH)
018 = 18,000 042 = 42,000
020 = 20,000 048 = 48,000
024 = 24,000 060 = 60,000
030 = 30,000 072 = 72,000
036 = 36,000
6
7
8System Type A = Air Conditioner
9Power Supply
(Volts-Hz-Phase)
A= 208/230-60-1 D= 460-60-3
C= 208/230-60-3 Z= 575-60-3
10
Heat Designation
@ Rated Voltage
000 = No Heat 080 = 8KW
022 = 2.2KW 090 = 9KW
036 = 3.6KW 100 = 10KW
040 = 4KW 120 = 12KW
050 = 5KW 150 = 15KW
060 = 6KW
11
12
13 Ventilation
Conguration
A = Solid Front Door
C = Economizer
D = Motorized Damper w/Pressure Relief
E = Motorized Damper w/Pressure Relief &
Independent Motorized Damper Control
F = No Free Cooling, 100% Emergency
Ventilation Only w/Independent Control
K = Economizer w/Factory Installed
CO2 Control
N = Barometric Damper w/15% OSA
+ = None
$ = Special
14 Dehumidication
G = Hot Gas Reheat
R = Electric Reheat
T = Electric Reheat w/Humidity Control
+ = None
$ = Special
15 Controls
A = Power Fail Alarm w/Additional Lockouts
C = 24V EMS Relay Kit
D = 24V EMS Relay Kit w/Factory
Installed T-Stat
E = Factory Installed T-Stat
+ = None
$ = Special
16 Operating Condition
A = Evaporator Freeze Sensor (EFS)
C = EFS w/Hot Gas Bypass
D = Desert Duty
F = Desert Duty w/Hard Start
G = Desert Duty w/EFS
H = Desert Duty w/Hard Start & EFS
N = Hard Start
P = Hard Start w/Low Ambient & CCH
Q = Hard Start w/Low Ambient &
Fan Cycle Control (FCC)
R = Crank Case Heater (CCH)
T = Hard Start w/EFS
U = Hard Start w/Hot Gas Bypass
V = Hard Start w/Low Ambient & CCH & EFS
W = Low Ambient w/CCH
Y = Low Ambient w/CCH & FCC
Z = Low Ambient w/CCH & EFS
1 = Low Ambient w/FCC
2 = Low Ambient w/FCC & EFS
+ = None
$ = Special
17 Indoor Air Quality Features
D = Dry Bulb Sensor
E = Dry Bulb Sensor w/Dirty Filter
G = Dirty Filter Sensor
M = Dry Bulb Sensor & CO2 Sensor
(Only w/Economizer)
+ = None
$ = Special
18 Air Flow
1 = Top Supply/Bottom Return
2 = Center Supply (Reverse)
3 = Bottom Supply/Top Return (Counter)
4 = Top Panel Discharge
5 = Centrifugal Blowers
6 = 3T3
7 = 3T5
8 = 4T2
9 = 4T3
A = 3T2
$ = Special
19 Compressor Location
C= Center - All 6 ton units
D= Left Hand - All 31/2 to 5 ton units
E= Right Hand - All 11/2 to 3 ton units
20 Filter Option
A = 2” Pleated (MERV 8, AC/HP-C)
C = 2” Charcoal
D = MERV 11 High Filtration Package
E = MERV 13 High Filtration Package
F = Filter Access Through Return Air Grille
W = Aluminum Washable
+ = None
$ = Special
21 Corrosion Protection
A = Condenser Coil Only
C = Evaporator Coil Only
D = Both Coils Condenser & Evaporator
E = All Coils Cond/Evap/Reheat
F = Coat All
G = Coastal Package & Evaporator Coil
K = Coastal Package
+ = None
$ = Special
22 Engineering Revision Level A1 B2 D2 D3
A2 C2 C3
23
24 Cabinet Color
1 = Marvair Beige
2 = Gray
3 = Carlsbad Canyon
4 = White
5 = Stainless Steel Exterior
6 = Dark Bronze
8 = Mesa Tan
9 = Pebble Gray
A = Stainless Steel - Unit
$ = Custom Color (Powder Coat)
25 Sound Attenuation 2 = Compressor Blanket
+ = None
26 Security Option
A = Lockable Access Plate/Tamper Proof
C = Tamper Proof Screws
D = Lockable Access Plate w/Tamper Proof
+ = None
$ = Special
27 Fastener/Drain Pan Option
A = Stainless Steel Fasteners
C = Stainless Steel Drain Pan
D = Stainless Steel Fasteners & Drain Pan
+ = None
$ = Special
28 Unused
C = Copeland Compressor
+ = None
$ = Special
29 Unused + = None
$ = Special
30 Special Variation
+ = None
$ = Special Conguration Not Covered by
Model Nomenclature
Note: Not all options are available with all congurations. Contact your Marvair sales representative for
conguration details and feature compatibility.

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
7
1.3 Serial Number Date Code
20 = 2020 01 = January 05 = May 09 = September
21 = 2021 02 = February 06 = June 10= October
22 = 2022 03= March 07 = July 11 = November
23 = 2023 04 = April 08 = August 12 = December
1.4 Air Flow, Weights and Filter Sizes
Complete electrical and performance specications and dimensional drawings are in the Marvair Wall
Mount Air Conditioner Product Data Sheets.
Note: Follow local codes and standards when designing duct runs to deliver the required airow.
Minimize noise and excessive pressure drops caused by duct aspect ratio changes, bends, dampers and
outlet grilles in duct runs.
Model 0.10 0.15 0.20 0.25 0.30 0.40 0.50
MAA1018A 685 670 670 642 640 600
MAA1020A 800 785 770 725 680 600
MAA1024A 800 785 770 725 680 600 500
MAA1030A 1200 1150 1100 1050 1000 900 800
MAA1036A 1290 1230 1170 1115 1060 1000 920
MAA1042A 1500 1430 1360 1295 1230 1160 1070
MAA1048A 1950 1900 1850 1815 1760 1680 1590
MAA1060A/MAA2072A & MGA1072A 1900 1850 1800 1700 1600 1500 1350
Values in bold are the minimum air flow.
Air flow ratings of 208-230 volt units are at 230v. Air flow ratings of 460 volt units are at 460 volts. Operation of units at a voltage different from the rating
point will affect air flow.
Table 1. CFM @ External Static Pressure (Wet Coil) (IWG)
Model INCHES MILLIMETERS PART NUMBER FILTERS PER UNIT MERV RATING
MAA1018A 14 x 12 1 356 x 305 x 25 P/80122 1N/A
MAA1020A/1024A 16 x 25 x 2 406 x 635 x 51 80137 1 8
MAA1024A/1030A/1036A "B2" INTERNAL 16 x 30 x 1 406 x 762 x 25 80136 1 N/A
MAA1024A "B2" RETURN GRILLE 11½ x 19½ x 1 292 x 495 x 25 91983 1 N/A
MAA1030A/1036A & MAA2072A 18 x 30 x 2 457 x 762 x 51 93184 1 8
MAA1030A/1036A "B2" RETURN GRILLE 27½ x 13½ x 1 699 x 343 x 25 80769 1 N/A
MAA1042A/1048A 36½ x 22 x 2 927 x 559 x 51 80162 1 8
MAA1060A 18 x 24 x 2 457 x 610 x 51 81257 2 8
MGA1072A 24 X 30 X 2 610 x 762 x 51 93587 1 8
Table 2. Return Air Filter Sizes
Model Weight Base w/Economizer w/3 Phase w/Economizer & 3 Phase
MAA1018A Pounds (Kilograms) 265 (120) N/A N/A N/A
MAA1020A/MAA1024A Pounds (Kilograms) 337 (153) 357 (162) 356 (161) 376 (171)
MAA1024A/1030A "B2" Pounds (Kilograms) 378 (171) 400 (181) 397 (180) 419 (190)
MAA1030A/MAA1036A Pounds (Kilograms) 397 (180) 419 (190) 416 (189) 438 (199)
MAA1036A "B2" Pounds (Kilograms) 380 (172) 403 (183) 418 (190) 441 (200)
MAA1042A/MAA1048A Pounds (Kilograms) 453 (205) 476 (216) 491 (223) 514 (233)
MAA1060A Pounds (Kilograms) 469 (213) 492 (223) 522 (237) 545 (247)
MAA2072A Pounds (Kilograms) 717 (325) 740 (336) 770 (349) 793 (360)
MGA1072A Pounds (Kilograms) 583 (264) 606 (275) 636 (288) 659 (299)
Table 3. Installed Weights for Marvair Wall Mount AC Units
1.5 General Operation
Model Ventilation Conguration Temperature Range
Non-Economizer Standard ("N"), Desert Duty ("ND") 0ºF – 131ºF (-18ºC – 55ºC)
With Economizer Standard ("CE"), Desert Duty ("CD") -40ºF – 131ºF (-40ºC – 55ºC)
Table 4. Ambient Temperature Operating Range

8
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
Model Refrigerant Charge (Oz) Model Refrigerant Charge (Oz)
MAA1018A 65 MAA1042A 123
MAA1020A 85 MAA1048A 128
MAA1024A 85 MAA1060A 125
MAA1024-1030A "B2" 110 MAA2072A 228
MAA1030A 105 MGA1072A 150
MAA1036A & "B2" 105 MGA2072A 145
Table 5. Refrigerant Charge (R410A, Ounces)
Refrigerant Cycle (Cooling Mode)
Marvair air conditioners use R-410A refrigerant in a conventional vapor-compression refrigeration cycle
to transfer heat from air in an enclosed space to the outside. A double blower assembly blows indoor air
across the evaporator. Cold liquid refrigerant passing through the evaporator is boiled into gas by heat
removed from the air. The warmed refrigerant gas enters the compressor where its temperature and pressure
are increased. The hot refrigerant gas condenses to liquid as heat is transferred to outdoor air drawn across
the condenser by the condenser fan. Liquid refrigerant is metered into the evaporator to repeat the cycle.
Heating Mode
A wall-mounted thermostat controls the heating cycle of models which incorporate resistance heating ele-
ments. On a call for heat, the thermostat closes the heat relay to energize the indoor fan and the resistance
elements. Except on units with the optional dehumidication kit, the compressor is locked out during the
heating cycle. Please see Appendix A for instructions on eld installing electric heaters.
Economizer Operation
The economizer is a regulated damper system with controls. The damper regulates the circulation of outside
air into the enclosure (when the outdoor air conditions are suitable) to reduce the need for mechanical
cooling, save energy, and extend compressor life.
Depending upon the options selected, the damper responds to the enthalpy of the outdoor air. On a call for
cooling from a space thermostat, it operates as follows:
When the enthalpy of the outdoor air is below the set point, the outdoor air damper is proportionally open
(and return air damper is proportionally closed) to maintain between 50°F and 56°F (10°C to 13°C) at the
mixed/discharge air sensor. Integral pressure relief allows the indoor air to exit the shelter through the air
conditioner.
When the enthalpy of the outdoor air is above the set point, the outdoor air damper closes to its minimum
position. A call for cooling from the space thermostat brings on mechanical cooling.
A built-in adjustable minimum position potentiometer controls the amount of outdoor air admitted to meet
minimum ventilation requirements.
1.6 Optional Controls & Packages
Hard Start Kit
Used on single phase equipment to give the compressor higher starting torque under low voltage conditions.
Generally not recommended on units with scroll compressors.
Protective Coating Packages
Typically only the non-economizer units are used in corrosive environments, but the air conditioners with
an economizer is also available with corrosion protection. 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).

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
9
The Coastal Environmental Package includes:
• Corrosion resistant fasteners
• Sealed or partially sealed condenser fan motor
• Protective coating applied to all exposed internal copper and metal in the condenser section
• Protective coating on the condenser coil (Luvata Insitu®) contains ES2 (embedded stainless steel
pigment) technology.
The Coat all Package includes all of the above, plus:
• Protective coating on the evaporator coil (Luvata Insitu®) contains ES2 (embedded stainless steel
pigment) technology
• Protective coating on exterior and interior components and sheet metal. (Note: the internal sheet
metal which is insulated, bottom outside panel, and the internal control box are not coated)
Electric Reheat Dehumidication
A humidity controller allows electric heat and cooling to operate simultaneously. Marvair®air conditioners
equipped with the dehumidication option allow the indoor humidity of the controlled environment
to be maintained at or below a certain humidity set point. These units do not have the ability to add
humidity to the building.
IMPORTANT
The electrical wire and breaker or fuses must be sized for simultaneous operation
of the electric heater and the air conditioner. Refer to the data sticker on the unit or
the appropriate Air Conditioner Product Data Sheet for the sizing information.
Dehumidication is achieved by operating mechanical cooling in conjunction with electric reheat. The
strip heat is sized approximately to the sensible capacity of the total tonnage of the machine (i.e., on a
24,000 BTU unit the strip heat is sized at approximately 20,000 BTU). Because the strip heat is sized
to the approximate sensible cooling capacity, only selected models are available.
Operation:
When the humidity rises above the set point on the humidity controller both mechanical cooling and
electric reheat operate to temper the air and lower the humidity. If the temperature in the controlled
environment rises above the set point of the thermostat and the unit is operating in the dehumidication
mode, the call for cooling will override the call for dehumidication and the strip heat is disengaged
until the thermostat is satised. This assures the environment temperature is maintained as rst priority
and humidity control is second.
In applications where a shelter has redundant air conditioning units and is controlled by a lead lag control-
ler (CommStat Touch, CommStat 4, CommStat 3 HVAC Controller), most times the dehumidication
option is only necessary on one of the two units. It is possible for one unit to be operating in the cooling
mode while the unit with dehumidication is operating at the same time. If the cooling unit does not
maintain the shelter temperature set point, the unit with dehumidication will go into the cooling mode.
It does not matter whether the unit with dehumidication is the lead or lag unit.
Three Phase Voltage Monitor
Continuously measures the voltage of each of the three phases. The monitor separately senses low
and high voltage, voltage unbalance including phase loss and phase reversal. An LED indicator glows
when all voltages are acceptable. Automatically resets when voltages and phases are within operating
tolerances. Not required on 1ø units.
Dirty Filter Indicator
A diaphragm type of indicator measures the air pressure on either side of the lter and when the pressure
drops below the set point, a red LED is illuminated. The set point is adjustable.

10
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
Protective Coil Coatings
Either the condenser or evaporator coil can be coated, however, coating of the evaporator coil is not
common. For harsh conditions, e.g., power plants, paper mills or sites were the unit will be exposed to
salt water, the condenser coil should be coated. Note: Cooling capacity may be reduced by up to 5%
on units with coated coils.
Thermal Expansion Valve
Available on all Marvair air conditioners. Improves performance in hot ambient temperatures.
High Filtration
Selected units are built with larger blowers/motors for use with higher efciency lters with MERV
ratings of 11, 13 and 14 when tested to ASHRAE 52.2. Units with economizers have a pre-lter on the
outside air.
Lockable Disconnect Access Cover Plate
The access plate to the service disconnect switch can be equipped with a lockable cover.
Cold Climate Kit
Controls and components which allow the units to operate in extremely cold temperatures. The kit
includes a suction line accumulator, thermal expansion valve (TXV), crankcase heater, hard start kit,
and an outdoor thermostat and fan cycle switch. The fan cycle control is standard on all Marvair air
conditioners and operates based upon the liquid line pressure. The outside thermostat opens whenever
the outside temperature is below 50°F (10°C) and closes when the outside temperature is 50°F (10°C)
or higher. Whenever the temperature is below 50°F (10°C), the fan cycle switch is in the circuit; when
temperatures are 50°F (10°C) or higher, the fan cycle switch is not in the circuit. The outdoor thermostat
is used with a TXV to prevent excessive cycling or “hunting” of the TXV.
Desert Duty
The Desert Duty package is a factory installed package of components and cabinet modications which
permit operation in harsh environments. To prevent sand and dust inltration, the electrical control
box is sealed. A closed loop design on non-economizer units insures that no outside air is introduced
into the shelter. Note: Units with an economizer may be ordered with the Desert Duty Package. If the
air conditioner is required with the Desert Duty Package, sand intrusion into the shelter should be
considered. Units without an economizer will operate from 20°F to 131°F (-7°C to 55°C). Economizer
equipped units will operate from -40°F to 131°F (-29°C to 55°C).
Cabinet Color and Material
Marvair air conditioners are available in three different cabinet colors -the standard Marvair beige,
white and gray. The standard cabinet’s sides, top and front panels are constructed of 20 gauge painted
steel. As an option, these panels can be built of 16 gauge steel in beige & gray. When the 16 gauge
painted steel or the aluminum is used, only the side, top and front panels are 16 gauge or aluminum.
Contact your Marvair representative for color chips. The cabinet can also be constructed of type 316
stainless steel. Two stainless steel cabinet constructions are available- the complete cabinet, including
most internal sheet metal or only the exterior sheet metal

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
11
1.7 Electrical Operation
The compressor and condenser fan are energized with a contactor controlled by a 24 VAC pilot signal.
Some compressors incorporate an internal PTC crankcase heater that functions as long as primary power
is available. The heater drives liquid refrigerant from the crankcase and prevents loss of lubrication
caused by oil dilution. 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. However, the motor is cycled on
and off by the low ambient control (see low ambient control 1.6).
The indoor evaporator fan motor is controlled by the fan purge on the electronic control board.

12
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
R
MFX
AV 0 4
2
Y
2 Y
1
L
B
101 O
201 KB
2
0
1
K
B
1
0
1
O
1
L
B
1
4
L
B
0
4
Y
2
2
1
R
B
1
2
1
K
B
2
2
1
R
B
2
2
1
K
B
0
4
Y
1
4
L
B
CN
" R " TATSOMREHT OT
"R" BT OT
"R" BCP OT
DED I VOR P Y A L E R
SR EHTO Y B GN I T S I X E TUN R E VE L
1 .GI F
G N I R I W T C A T N O C NWO D T U H S M E T S Y S
4
0
2
Y7
1
2
O
6
1
2
K
B
712 O
612 KB
612 R
812 RB
402 Y
502 LB
502 LB
612 R
812 RB
012 KB
702 Y
212 RB
112 O
802 LB
902 R
012 KB
702 Y
212 RB
36 KB 26 KB
2
6
K
B
1 6 T HW
102 KB
102 KB
202 LB
202 LB
CH
R
E
T
A
E
H
4
0
2
Y7
1
2
O
6
1
2
K
B
712 O
612 KB
612 R
812 RB
402 Y
502 LB
502 LB
612 R
812 RB
012 KB
702 Y
212 RB
112 O
802 LB
902 R
012 KB
702 Y
212 RB
36 KB 26 KB
2
6
K
B
1 6 T HW
102 KB
102 KB
202 LB
202 LB
CH
R
E
T
A
E
H
4
0
2
Y
6
1
2
K
B
612 KB
612 R
402 Y
502 LB
502 LB
612 R
012 KB
702 Y
802 LB
902 R
012 KB
702 Y
36 KB 26 KB
2
6
K
B
1 6 T HW
102 KB
102 KB
202 LB
202 LB
CH
R
E
T
A
E
H
R
E
T
A
E
H
202 LB
102 KB
G
R
9
1
1
T
H
W
0
2
1
K
B
021 KB
9 1 1 T HW
R
G
V01 - 0 C
OC E
V01 - 0 C
MFO
MW P
MB I
+- +- +- +-
SE S DO SA S SD
DNG DNG
1CC F 2CC F
RB I
HR
VR
HE
RFO
1CC
2CC
UNEM
PU
NWO D
RC C R ON MOC CN 1Y 2Y MUH G 2W O VE CF
MR A L A
T UOK CO L
O N MO C C N
SUTA T S
. ONO C E
1 S PH 2 S PH
DNG DNG
1SPL 2SP L
1 T R O P MM O C 2 T R O P MM O C
V01 - 0
C
MW P
98529 DRAOB T IUCRI C DETNIRP
R E WO P DE L
63 KB 53 KB
73 KB
S NO I T C E NNO C MR A L A DN A T A T S OMR E H T
0
3
1
Y
8
2
1
K
B
7
2
1
K
B
131 R
131 R
721 KB
821 KB
802 LB
702 Y
8
0
2
L
B
702 Y
521 KB
621 R
6
2
1
R
5
2
1
K
B
102 KB
401 LB
301 KB
202 LB
301 KB
102 KB
401 LB 202 LB
3
2
1
R
3
2
1
R
421 Y
9
1
K
B
21 LB
0
3
1
Y
26 KB36 KB
1 6 T HW
2
6
K
B
1
6
T
H
W
21 LB
6
K
B
6 KB
3
1
K
B
3
1
K
B
61 KB
6
1
K
B
9
1
K
B
3
6
K
B
6
0
1
K
B
7
0
1
L
B5
0
2
L
B
4
0
2
K
B
CH
C
C
RE TA EH
R O S S E R P MO C
5
R
7
R
1 . GI F EES
S NO I T PO D E L L A TN I
SNO I TPO DE L L ATSN I
NO I T PO T A E HE R C I R T C E L E
R O S S E R P MOC E G A T S 2
R E PMAD " F " RO " D " DE Z I ROTOM
R E Z I MON O C E
Y P L AHTN E
B LUB Y RD
T A E HE R S AG TOH
RO
DROCER NO I S I VER RD KCMY SOC E E T AD
EGNAHCRE TN I , C AV 02 2 NAHT S SE L S EGAT LOV ROF . NO I TARE PO C AV 0 4 2 ROF DE P P AT Y ROT C A F S I R EMROF SNA RT L OR TNOC
Ø1 zH06 TLOV 032 / 802 . NWOHS RKB T KC L ANO I T PO . E Z I S E SUF DNA YT I CAPMA ROF ETAL P ATAD EE S . Y L PPUS REWOP
.2
.1
. SDAE L DESUNU ETA LUSNI , NOI TAREPO CAV802 ROF S I ER IW PAT REMROFSNART DER EHT . SER IW PAT REMROSNART EGNARO DNA DER
. SROSSERPMOC L LA NO DER I UQER EB TON YAM RETAEH ESACKNARC
.3
.TUOKCOL LLIW TINU EHT DNA ECIWT DENEPO SAH SPH EHT NEHW )TLUAF ERUSSERP HGIH( A ROF " 2F / 1F" "PH" YALPS ID LL IW )YALPSID SUTATS( EHT
.4
. TUOKCOL L L IW T I NU EHT DNA GN I ZE ERF S E SNES ROSNE S NO I TCUS EHT NEHW ) T LUA F ERUS SERP WOL ( A ROF " 2 F / 1 F " " PL " YALPSID LL IW )YALPSID SUTATS ( EHT
STNEMTSUJDA ELBALIAVA LLA ROF LAUNAM O/ I TCUDORP EHT EES .UNEM YALPSID DRAOB NO EHT HTIW ENOD EB YAM METSYS EHT OT STNEMTSUJ SA ELBAL I AVA L LA. 5
. S GN I T T E S DNA
YROTCAF EGAT LOV EN I L
Y ROT C A F E G A T L O V WO L
NE ERG - G
NWORB - RB WO L L E Y - Y
E DO C RO L OC
E T I HW - T HW
EGNA RO - O
EUL B - L B
KCAL B - KB
DER - R
D L E I F E G A T L O V WO L
DL E I F EGAT LOV EN I L
) . CEPS DLE I F ( EGATLOV . TLA
51013 AG , e l ed r oC 004 xoB OP
T I NU
0
BJ
NWO R B . J
BJ BJ
32/51/20
27132
STN
32 / 51 / 20
A AM
0R - 3C -B -AA060 - 420AAM
WK51 - 5 ACA 06 - 42 AAM
WK51 - 50 HT IW HP1 V032 /802 AAM
R E L L OR TNOC C I GO L E L B AMMA R GO R P
R O T OM T S U A H X E
HCT IWS E RU S S E RP HG I H
ROTOM R EWOL B ROODN I
HCT IWS E RU S S E RP WO L
L OR TNO C D E E P S NA F
S PH
SPL
MB I
MX E
CSF
R O S S E R P MO C
ROS NE S T SOR F ED
RETAEH ESACKNARC
ROT CA T NOC ROS S E PRMOC
ROT I C A P A CC
P MO C
HCC
S FD
CC
ROTOM R I A ROODTUO
ROTOM NA F ROOD T UO
Y A L E R N A F ROOD T UO
D I ONELOS EV L AV GN I SREVER
MFO
CLP
SVR
RFO
MAO
Y
ALER LORTNOC ELCYC NAF
LORTNOC ELCYC NAF
RCC F
CCF
D I ON E L OS T A E H E RSHR
LEEHW NEERGWG
YRTNE REWOP TNIOP ELGNISEPPS
YAL ER REWOLB ROODN IRB I
R O T OM R I A H S E R FMA F
R E M R O F S N A R TR M F X
R O T OM NO I T A L I T N E VMV Y A L E R R O T O M N O I T A L I T N E VR M V
T IMI L EMI T ENOL TO
RE T AEH C I RTC E LEHE
L OR TNO C R E Z I MONOC ECE
Y A L ER T SOR F EDRFD
ROSNE S Y P LAHTNESE
ROT AU T CA R E PMADAD
R O T I N OM E S A H PMP
S NO I T C ENNOC T A T S OMR E HT
CAV4 2 - R
N OMMO C - C
PMOC EGATS 1 - 1Y
P MO C E G A T S D N 2 - 2 Y
NO I T A C I F I D I MUHED - MUH
NA F - G
TAEH C IRTCELE - 2W
EVLAV GN I SREVER - O
TNEV YCNEGREME - VE L OOC D E C RO F - C F
51105 / K , 31105 /K
. c n I , S CXR I A
r i av r aM
AG , e l e d r oC
. c n I , SCXR I A
r i av r aM
AG , e l e d r oC
Y B NWA R D
Y B D E VORP P A
. VER
R E B M U N G N I WA R D
RA LUGN A
S E CNA R E L OT
DE TON S A
± ±
E T AD
TPECX E
L A NO I T C A R F
±
L AM I C E D
ELT I T
E L ACS
DNEGE L EGAT LOV
S E TON L A R E N E GDNEGE L L AC I RTCE L E
V42
RC
V042
2A
1A
Figure 1a. Typical Electrical Schematic - (Non-Economizer) Model MAA

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
13
65 R
55 KB
65 R
55 KB
1 5 YG
25 KB 35 R
1 5 YG
25 KB 35 R
25 KB
1 5 YG
35 R
91105 /K ROSNES . TNE
ROSN E S Y P L AHTN E
X
R
MFX
AV 0 4
2
Y
2 Y
1
L
B
101 O
201 KB
2
0
1
K
B
1
0
1
O
1
L
B
1
4
L
B
0
4
Y
2
2
1
R
B
1
2
1
K
B
2
2
1
R
B
2
2
1
K
B
0
4
Y
1
4
L
B
CN
" R " TATSOMREHT OT
"R" BT OT
"R" BCP OT
DED I VOR P Y A L E R
SR EHTO Y B GN I T S I X E TUN R E VE L
1 .GI F
G N I R I W T C A T N O C NWO D T U H S M E T S Y S
4
0
2
Y7
1
2
O
6
1
2
K
B
712 O
612 KB
612 R
812 RB
402 Y
502 LB
502 LB
612 R
812 RB
012 KB
702 Y
212 RB
112 O
802 LB
902 R
012 KB
702 Y
212 RB
36 KB 26 KB
2
6
K
B
1 6 T HW
102 KB
102 KB
202 LB
202 LB
CH
R
E
T
A
E
H
4
0
2
Y7
1
2
O
6
1
2
K
B
712 O
612 KB
612 R
812 RB
402 Y
502 LB
502 LB
612 R
812 RB
012 KB
702 Y
212 RB
112 O
802 LB
902 R
012 KB
702 Y
212 RB
36 KB 26 KB
2
6
K
B
1 6 T HW
102 KB
102 KB
202 LB
202 LB
CH
R
E
T
A
E
H
4
0
2
Y
6
1
2
K
B
612 KB
612 R
402 Y
502 LB
502 LB
612 R
012 KB
702 Y
802 LB
902 R
012 KB
702 Y
36 KB 2 6 KB
2
6
K
B
1 6 T HW
102 KB
102 KB
202 LB
202 LB
CH
R
E
T
A
E
H
R
E
T
A
E
H
202 LB
102 KB
G
R
9
1
1
T
H
W
0
2
1
K
B
021 KB
9 1 1 T HW
R
G
V01 - 0 C
OC E
V01 - 0 C
MFO
MW P
MB I
+- +- +- +-
SE S DO SA S SD
DNG DNG
1CC F 2CC F
RB I
HR
VR
HE
RFO
1CC
2CC
UNEM
PU
NWO D
RC C R ON MOC CN 1Y 2Y MUH G 2W O VE CF
MR A L A
T UOK CO L
O N MO C C N
SUTA T S
. ONO C E
1 S PH 2 S PH
DNG DNG
1SPL 2SP L
1 T R O P MMO C 2 T R O P MMO C
V01 - 0
C
MW P
98529 DRAOB T IUCRI C DETNIRP
R E WO P DE L
63 KB 53 KB
73 KB
S NO I T C E NNO C MR A L A DN A T A T S OMR E H T
0
3
1
Y
8
2
1
K
B
7
2
1
K
B
131 R
131 R
721 KB
821 KB
802 LB
702 Y
8
0
2
L
B
702 Y
521 KB
621 R
6
2
1
R
5
2
1
K
B
102 KB
401 LB
301 KB
202 LB
301 KB
102 KB
401 LB 202 LB
3
2
1
R
3
2
1
R
421 Y
9
1
K
B
21 LB
0
3
1
Y
26 KB36 KB
1 6 T HW
2
6
K
B
1 6
T
H
W
21 LB
6
K
B
6 KB
3
1
K
B
3
1
K
B
61 KB
6
1
K
B
9
1
K
B
3
6
K
B
6
0
1
K
B
7
0
1
L
B5
0
2
L
B
4
0
2
K
B
CH
C
C
RE TA EH
R O S S E R P MO C
5
R
7
R
1 . GI F EES
S NO I T PO D E L L A TN I
SNO I TPO DE L L ATSN I
NO I T PO T A E HE R C I R T C E L E
R O S S E R P MOC E G A T S 2
R E PMAD " F " RO " D " DE Z I ROTOM
R E Z I MON O C E
Y P L AHTN E
B LUB Y RD
T A E HE R S AG TOH
RO
DROCER NO I S I VER RD KCMY SOC E E T AD
EGNAHCRE TN I , C AV 02 2 NAHT S SE L S EGAT LOV ROF . NO I TAR E PO C AV 0 4 2 RO F DE P P A T Y ROT C A F S I R EMROF SNA RT L OR TNOC
Ø1 zH06 TLOV 032 / 802 . NWOHS RKB T KC L ANO I T PO . E Z I S E SUF DNA YT I CA PMA ROF ETA L P ATAD EES . Y LPPUS REWOP
.2
.1
. SDAE L DESUNU ETA LUSNI , NOI TAREPO CAV802 ROF S I ER IW PAT REMROFSNART DER EHT . S ER IW PAT REMROSNART EGNARO DNA DER
. SROSSERPMOC L LA NO DER I UQER EB TON YAM RETAEH ESACKNARC
.3
.TUOKCOL LLIW TINU EHT DNA ECIWT DENEPO SAH SPH EHT NEHW )TLUAF ERUSSERP HGIH( A ROF " 2F/ 1F" " PH" YALPS ID LL IW )YALPSID SUTATS( EHT
.4
. TUOKCOL L L IW T I NU EHT DNA GN I ZE ERF S E SNES ROSNE S NO I TCUS EHT NEHW ) T LUA F ERUS SERP WOL ( A ROF " 2 F / 1 F " " PL " YALPS ID LL IW ) YALPS ID SUTATS ( EHT
STNEMTSUJDA ELBALIAVA LLA ROF LAUNAM O/ I TCUDORP EHT EES .UNEM YALPSID DRAOB NO EHT HTIW ENOD EB YAM METSYS EHT OT STNEMTSUJ SA ELBAL I AVA L LA. 5
. S GN I T T E S DNA
YROTCAF EGAT LOV EN I L
Y ROT C A F E G A T L O V WO L
NE ERG - G
NWORB - RB WO L L E Y - Y
E DO C RO L OC
E T I HW - T HW
EGNA RO - O
EUL B - L B
KCAL B - KB
DER - R
D L E I F E G A T L O V WO L
DL E I F EGAT LOV EN I L
) . CEPS DLE I F ( EGATLOV . TLA
51013 AG , e l ed r oC 004 xoB OP
T I NU
0
BJ
NWO R B . J
BJ BJ
32/51/20
27132
STN
32 / 51 / 20
A AM
0R - 3C -B -AA060 - 420AAM
WK51 - 5 ACA 06 - 42 AAM
WK51 - 50 HT IW HP1 V032 /802 AAM
R E L L OR TNOC C I GO L E L B AMMA R GO R P
R O T OM T S U A H X E
HCT IWS E RU S S E RP HG I H
ROTOM R EWOL B ROODN I
HCT IWS E RU S S E RP WO L
L OR TNO C D E E P S NA F
S PH
SPL
MB I
MX E
CSF
R O S S E R P MO C
ROS NE S T SOR F ED
RETAEH ESACKNARC
ROT CA T NOC ROS S E PRMOC
ROT I C A P A CC
P MO C
HCC
S FD
CC
ROTOM R I A ROODTUO
ROTOM NA F ROOD T UO
Y A L E R N A F ROOD T UO
D I ONELOS EV L AV GN I SREVER
MFO
CLP
SVR
RFO
MAO
Y
ALER LORTNOC ELCYC NAF
LORTNOC ELCYC NAF
RCC F
CCF
D I ON E L OS T A E H E RSHR
LEEHW NEERGWG
YRTNE REWOP TNIOP ELGNISEPPS
YAL ER REWOLB ROODN IRB I
R O T OM R I A H S E R FMA F
R E M R O F S N A R TR M F X
R O T OM NO I T A L I T N E VMV Y A L E R R O T O M N O I T A L I T N E VR M V
T IMI L EMI T ENOL TO
RE T AEH C I RTC E LEHE
L OR TNO C R E Z I MONOC ECE
Y A L ER T SOR F EDRFD
ROSNE S Y P LAHTNESE
ROT AU T CA R E PMADAD
R O T I N OM E S A H PMP
S NO I T C ENNOC T A T S OMR E HT
CAV4 2 - R
N OMMO C - C
PMOC EGATS 1 - 1Y
P MO C E G A T S D N 2 - 2 Y
NO I T A C I F I D I MUHED - MUH
NA F - G
T A E H C I R T C E L E - 2W
EVLAV GN I SREVER - O
TNEV YCNEGREME - VE L OOC D E C RO F - C F
51105 / K , 31105 /K
. c n I , S CXR I A
r i av r aMAG , e l e d r o C
. c n I , SCXR I A
r i av r aM
AG , e l e d r oC
Y B NWA R D
Y B D E VORP P A
. VER
R E B M U N G N I WA R D
RA LUGN A
S E CNA R E L OT
DE TON S A
± ±
E T AD
TPECX E
L A NO I T C A R F
±
L AM I C E D
ELT I T
E L ACS
DNEGE L EGAT LOV
S E TON L A R E N E GDNEGE L L AC I RTCE L E
V42
RC
V042
2A
1A
Figure 1b. Typical Electrical Schematic - (Economizer) Model MAA

14
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
Figure 1c. Typical Electrical Schematic - (Economizer) Model MAA (Alternate Construction)

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
15
Figure 1d. Typical Electrical Schematic - (Economizer) Model MAA (Alternate Construction)

16
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22

 
Figure 1e. Typical Electrical Schematic - (Economizer), Model MAA (Alternate Construction)

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
17
Chapter 2 Electronic Control Board
2.1 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.
Marvair’s proprietary Printed Circuit Board (PCB) sets the standard for the industry in flexibility,
reliability and performance. This UL certified component is engineered to optimize Heating, Cooling and
Dehumidification operation while communicating valuable information to the end user. Special features
include 2-Stage operation with varying speed control to optimize latent and sensible capacity, built in
remote communication (Modbus) for monitoring and/or control, optimized head pressure control and
configurable menu options for various operations and control. The Marvair PCB comes equipped with
seven segment display to annunciate faults, which drastically reduces troubleshooting time and system
downtime. Lockout contacts are also provided along with the alarms being transferred via 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. See I/O table.
1
16
17
18
19
20
21
22
23
2 3 4 5 6 7
121315 14
9 10
11
8

18
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
Item Description
1Economizer Actuator Output 2-10 VDC
2Outdoor Motor Control Output 0-10 VDC or PWM
3Indoor Motor Control Output 0-10 VDC or PWM
4Enthalpy Sensor Signal Input 4-20mA
5Outdoor Sensor Signal 10K NTC (Heat Pumps) / Dry Bulb Sensor Signal Input 10K NTC
(Systems Equipped with Dry Bulb Economizer)
6Supply Air Sensor Signal Input 10K NTC (Systems Equipped with Economizer)
7Defrost Sensor Signal Input 10k NTC (Heat Pumps Only)
8Head Pressure Control Sensor Signal 10k NTC (ECM Motors)
9Control Board Menu/Fault Display
10 Menu/Up/Down Selection Buttons
11 Modbus RJ11 Communications Ports
12 Low Pressure / Freeze Sensor Signal Input 10k NTC
13 High Pressure Switch Input (Normally Closed)
14 Thermostat Inputs/Alarm And Status Terminals
15 24 VAC To Power Board (18 VAC To 30 VAC)
16 Indoor Blower Output 24 VAC (PSC Motors)
17 Reheat Output 24 VAC (Hot Gas Or Electric Reheat Dehumidication)
18 Reversing Valve Output 24 VAC (Heat Pumps Only)
19 Electric Heat Output 24 VAC
20 Outdoor Fan Output 24 VAC (PSC Motors)
21 Compressor 1/1st Stage Output 24 VAC (Single Stage Compressor)
22 Compressor 2/2nd Stage Output 24 VAC (Dual Compressor System 2nd Compressor)
(Single Compressor 2nd Stage)
23 Control Board Power Indicator LED
2.2 Installation and Replacement
The PCB is factory installed. To install a replacement PCB, use the six mounting holes along with the
appropriate screw size to rmly secure the board to the control box. After this is achieved, follow the
wiring diagram and menu conguration for the respective system for appropriate operation. Ensure
that the terminals used do not make any unwanted electrical connection (via strands etc.) with any
other terminals. Please allow a 1” creepage distance between the board and all other adjacent electrical
components.
2.3 PCB Details and Information
The PCB is equipped with an on board seven-segment display (Item #9) for
conguring various settings and displaying faults. During normal operation the
display remains off unless the conguration menu is accessed or a fault has occurred.
Faults will be annunciated on the display as shown below:
Display Displayed Faults
AS-F Supply Air Sensor Fault (Sensor Disconnected Or Faulty) If Equipped
DB-F Dry Bulb / Outdoor Sensor Fault (Sensor Disconnected Or Faulty) If Equipped
DS-F Defrost Sensor Fault (Sensor Disconnected Or Faulty) Heat Pumps Only
ES-F Enthalpy Sensor Fault (Sensor Disconnected Or Faulty) If Equipped
LP-1 Low Pressure Lockout Compressor Circuit 1
LP-2 Low Pressure Lockout Compressor Circuit 2
HP-1 High Pressure Lockout Compressor Circuit 1
HP-2 High Pressure Lockout Compressor Circuit 2
03 Low Voltage "Brownout" 16VAC or Less for 10 Minutes

Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
19
2.3.1 – Programming Menu Conguration
1. To Enter Programming Mode:
• Press and hold the Menu button for 5 seconds until P-01 is displayed.
2. While in Programming Mode main menu:
• Press the Menu button to enter the displayed parameter menu.
• Press the Up/Down buttons to adjust the current parameter number.
• The current parameter number will be displayed seven segments alternating showing "P-"
and the number every 0.5s.
3. While in parameter menu:
• The current parameter selection will be displayed seven segments.
• Press the Menu button to save the current parameter selection return to the programming
main menu.
• Press the Up/Down buttons to adjust the current parameter selection.
4. To exit programming mode, press and hold the Mode and Up buttons while in the programming
main menu.
• Press and hold the Menu button for 5 seconds.
• Note: The control will automatically exit the programming mode after 2 minutes with no
activity.
Note: 100 will be displayed by alternating between "1" and "00" every 0.5s.
Conguration Menu
Menu
Setting Name Default Selections General Description
1AC/HP Select AC AC, HP HP = Heat Pump Unit, AC = AC Unit
2IBM Select P P, dC P = PWM, dC = 0-10V
3FAN PURGE 90 N, 10-90 Indoor Blower off delay in seconds
4IBM Y1 Set 80 40-100 “G” Fan only and “Y1” 1st Stage Cooling Indoor Blower
Speed Setting
5IBM Y2 Set 100 40-100 “Y2” 2nd Stage Cooling Indoor Blower Speed Setting
6OFM Select P P, dC P = PWM, dC = 0-10V
7OFM Set 80 65-100 Outdoor Fan Motor Max Speed setting
8Defrost Timer 30 30, 60, 90 Defrost cycle timer in minutes
9EHDD select Y Y, n CAN ONLY BE "Y" IF SCKT IS "N"
10 SCKT select n Y, n SCKT= Y OVERRIDES EHDD
11 ODS set 50 0-70 Outdoor Sensor for HP or Econo. Dry Bulb Setpoint
12 ECONO select n Y, n n = Disabled (No Econo.), Y = Enabled (W/Econo.)
13 Sensor Type EN EN or DB Economizer sensor type selection EN= Enthalpy, DB = Dry Bulb
14 ECONO set d A-E Selections A=73F, B=70F, C= 67F, D =63F E= 55F all @
50%RH (Only available if EN sensor type is se-lected)
15 MIN POS 20 20-100 Sets the damper position for Minimum Open
16 W2 speed 100 70-100 Sets the Indoor Blower Speed for Electric Heat
17 Dehum speed 80 60-100 Sets the Indoor Blower Speed for Dehumidication
18 DS calibration 0-18 Defrost Sensor Calibration
19 SAS calibration 0-18 Supply Air Sensor Calibration
20 T'STAT Select H H, C H = hardwired 24V Tstat, C = communicating Tstat
21 Modbus ID 1 36161 Sets the Modbus ID for the unit
22 Modbus BAUD rate 19 9.6, 19 Available Baud Rates 9.6 = 9600, 19 = 19200
23 Modbus timeout 25 21916 Communications Timeout in minutes
24 Test n Y, n When set to “Y” all timers are reduced for testing
25 SW version number N/A N/A Displays the current version software

20
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
06/2023 Rev.22
Conguration Menu Details
1. AC/HP Select: This setting allows the PCB to be congured for AC (air-conditioner) or HP (heat-
pump). The system type is congured at the factory during production testing for the appropriate
system type. The default system type is AC.
2. IBM Select: This setting allows the IBM (Indoor Blower) control signal to be congured for
PWM or 0-10vdc control. The default control output signal is PWM.
3. Fan Purge: This setting allows the delay off time of the indoor blower once the call for the indoor
blower has been removed. The selections are N (no delay) or 10-90 seconds. After the default time
of 90 seconds the indoor blower will shut off. Selecting the N (no delay) will allow the Indoor
blower to shut off immediately after any request has been removed.
4. IBM Y1 Set: This is an independent setting for the speed at which the Indoor blower will operate
upon a request for Y1 (1st stage cooling) via Digital Input or Modbus. The default setting for
the IBM Y1 Set is 80% of maximum speed. The speed may be adjusted from 40-100% in 1%
increments to meet desired airow requirements. Note: Adjusting the speed too low will result
in coil freezing.
5. IBM Y2 Set: This is an independent setting for the speed at which the Indoor blower will operate
upon a request for Y2 (2nd stage cooling) via Digital Input or Modbus. The default setting for
the IBM Y1 Set is 100% of maximum speed. The speed may be adjusted from 40-100% in 1%
increments to meet desired airow requirements.
Note: Adjusting the speed too low will result in coil freezing, low-pressure or high-pressure lockout.
6. OFM Select: This setting allows the IBM (Indoor Blower) control signal to be congured for
PWM or 0-10vdc control. The default control output signal is PWM.
7. OFM Set: This is an independent setting for the max speed at which the Outdoor fan will operate.
The default setting for the OFM Set is 80% of maximum speed. The speed may be adjusted from
65-100% in 1% increments to meet desired airow requirements.
Note: Adjusting the speed too low will result in coil freezing, low-pressure or high-pressure lockout.
8. Defrost Timer: The defrost timer only applies to Heat-pump systems (when setting 1 is set to
HP). This is the accumulation timer used to monitor for heat-pump defrost control. The selections
for defrost timing is 30, 60 and 90 minutes. The defrost timer accumulates the compressor runtime
in the heat-pump mode and monitors the defrost sensor for freezing conditions to initiate a defrost
cycle at the selected defrost timing interval. The default defrost time is 30 minutes.
9. EHDD Set: The Electric heat during defrost setting allows the electric heat to operate when a
defrost cycle is being performed in heat-pump mode. The selections for the EHDD Set are Y (yes)
or N (no). When set to N (no) the electric heat will not operate automatically during a defrost
cycle in heat-pump mode. When the EHDD Set is set to Y (yes, Default) the electric heat will
operate upon each defrost cycle in the heat-pump mode.
Note: EHDD and SCKT cannot both be set to the Y (yes) selection at the same time. SCKT takes
priority over EHDD.
10. SCKT Set: The SCKT setting is used to prevent simultaneous operation of the electric heat and
compressor. The selections for the SCKT Set are Y (yes) or N (no). When set to N (no, Default)
the electric heat will be allowed to operate with the compressor in heat-pump mode upon a call