Marvair AVPA 12 series User manual

MODELS:
AVPA 12-20-24-30-36-42-48-60
Installation & Operation Manual
9 EER Vertical Wall-Mount Air Conditioners
Manufactured By:
A Division of the AIRXCEL®Commercial Group
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.
Air Conditioner Product Manual
Vertical Wall-Mount Air Conditioners
with Front Control Box Panel
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 ModPac Installation & Operation Manual 11/2017 Rev. 8
Part #01690

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Specications subject to change without notice.
© 11/2017 Airxcel Commercial Group
How To Use This Manual
This manual is intended to be a guide to the Marvair® ModPac 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 ModPac 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 ModPac 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 [phone] 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 ModPac unit and in the instruction
manuals be alert to the potential for personal injury. Understand the signal word DANGER, WARNING
and CAUTION. 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 info that will result in improved installation, reliability or
operation.

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Table of Contents
Chapter 1. ModPac Description & Specications
1.1 General Description..................................................................................................................................5
1.2 Model Identication .................................................................................................................................5
1.3 Serial Number Date Code ........................................................................................................................5
1.4 General Operation ....................................................................................................................................6
1.5 M5 Conguration .....................................................................................................................................6
1.6 A2 Internal Disconnect.............................................................................................................................6
1.7 Elcontronic Control Board Modes of Operation ......................................................................................6
1.8 Electrical Diagrams ..................................................................................................................................8
Chapter 2. Installation
2.1 Equipment Inspection.............................................................................................................................10
2.2 Installation Requirements.......................................................................................................................10
2.3 Installation Materials..............................................................................................................................12
2.4 Porting and Duct Work...........................................................................................................................14
2.5 Fresh Air Hood Installation ....................................................................................................................15
2.6 Bottom Bracket Installation ...................................................................................................................15
2.7 Mounting the Unit ..................................................................................................................................16
2.8 Electrical Connections............................................................................................................................17
Chapter 3. Start-Up
3.1 Check-Out of Cooling Cycle .................................................................................................................20
3.2 Check-Out of Heating Cycle ..................................................................................................................20
Chapter 4. Troubleshooting
4.1 Overview ................................................................................................................................................21
4.2 Failure Symptoms Guide........................................................................................................................22
4.3 Compressor Troubleshooting .................................................................................................................23
4.4 Electric Heat Controls ............................................................................................................................24
Chapter 5. Ratings & Specications
5.1 Ratings & Specications .......................................................................................................................25
Chapter 6. Maintenance
6.1 Scheduled Maintenance..........................................................................................................................26
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.

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Chapter 7. Warranty Information
7.1 Airxcel Commercial Group Limited Product Warranty Statement ........................................................27
Exploded Views & Parts Lists .......................................................................................................................28
Appendix A - Installation Instructions of Field Installed Electric Heat ........................................................28
Illustrations
Figure 1. Typical Electrical Schematic for Units with the PC Board .....................................................9
Figure 2. Damper Air Path ....................................................................................................................12
Figure 3a. Fresh Air Hood Adjustment for Models AVPA20-60 ............................................................15
Figure 3b. Fresh Air Hood Adjustment for AVPA12...............................................................................15
Figure 4. Wall Mounting Detail.............................................................................................................16
Figure 5. Thermostat Connection Diagram...........................................................................................19
Figure 6. Typical Conguration for Single Element Heater..................................................................24
Tables
Table 1. Minimum Clearances............................................................................................................. 11
Table 2. Voltage Limitations................................................................................................................ 11
Table 3. Maximum Static Pressure ......................................................................................................15
Table 4. CFM @ ESP...........................................................................................................................25
Table 5. Filter Sizes .............................................................................................................................25
Table 6. Shipping Weights ...................................................................................................................25

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Chapter 1. Description & Specications
1.1 General Description
The Marvair® ModPac air conditioner line is a series of vertical wall-mounted air conditioning systems
that provide heating and cooling for modular construction ofces and classrooms. The series includes
four cabinet sizes and nominal cooling capacities from 12,000 to 56,500 BTUH. Resistance heating
elements are available in various wattages. See Appendix A for instructions on eld installation of
electric heat.
Marvair's ModPac models are designed for easy installation and service. Major components are accessible
for service beneath external panels.
1.2 Model Identication
AVP A •AC •••• M5 •••••• •••
Air Source
Vertical Package
Nominal Cooling
12 = 12,000 BTUH
20 = 20,000 BTUH
24 = 24,000 BTUH
30 = 29,000 BTUH
36 = 35,000 BTUH
42 = 42,000 BTUH
48 = 46,500 BTUH
60 = 56,000 BTUH
System Type
Air Conditioner
Power Supply
A = 208/230V,1ø,60Hz
C = 208/230V,3ø,60Hz
D = 460V,3ø,60Hz
Configuration
M5 =PC Board &
Square Cornered
Cabinet
Electric Heat – kW
000 = No Heat 080 = 8 kW
036 = 3.6 kW 090 = 9 kW
040 = 4 kW 100 = 10 kW
050 = 5 kW 120 = 12 kW
060 = 6 kW 150 = 15 kW
Ventilation Code
N = 0-15% fresh air with manual damper,
no pressure relief)
All Models
B = Motorized two position damper
(open & closed) capable of 0
to 450 cfm (up to 40% of rated
air flow) of outside air, includes
pressure relief) Models AVPA30-
60 only
Z = Manual damper, field adjustable with
pressure relief
Y = Manual damper, field adjustable, no
pressure relief
A = R410
Refrigerant
Special Option Code
U = Scroll Compressor
A1 = PC Board
K = Coastal Environmental
Package
R = Electric Reheat
Color Code
800 = Mesa Tan
200 = Grey
400 = White
A5 = Built in
compliance with
UL 1995, 4th
edition
Brand Designation
Unused = Marvair
ModPac
EUB = Eubank
WalPac
1.3 Serial Number Date Code
A = January E = May J = September D = 2014 H = 2018
B = February F = June K = October E = 2015 I = 2019
C = March G = July L = November F = 2016 J = 2020
D = April H = August M = December G = 2017 K = 2021

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1.4 General Operation
Refrigerant Cycle (Cooling Mode)
The ModPac uses 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. 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 blown across
the condenser by the condenser fan. Liquid refrigerant is metered into the evaporator through capillary
tubes to repeat the cycle.
Heating Mode
A wall-mounted thermostat controls the heating cycle of models which incorporate resistance heating
elements. On a call for heat, the thermostat closes the heat relay to energize the indoor fan and the
resistance elements. Please see Appendix A for instructions on eld installing electric heaters.
Ventilation Options
• Manual damper capable of up to 15% of rated airow of outside air; eld adjustable, no pressure
relief. (Standard - Ventilation Conguration N)
• Motorized, two position damper (open and closed) capable of 0 to 450 cfm (maximum of 40% of
rated airow) of outside air; includes pressure relief. A 24-volt actuated motor controls the damper
from an external input such as: a time clock, CO2 sensor, energy management system or manual
switch. (Optional - Ventilation Conguration B) - AVPA20-60 only.
• Field adjustable manual damper capable of up to 450 cfm (maximum 40% of rated airow) of outside
air; includes pressure relief. (Ventilation Conguration Z) – AVPA20-60 only.
• Field adjustable manual damper capable of up to 450 cfm (maximum 40% of rated airow) of outside
air. Does not include pressure relief. (Ventilation Conguration Y) – AVPA20-60 only.
1.5 M5 Conguration
The M5 conguration of the ModPac conditioners include a factory installed PC board.
The internal control board in the M5 conguration simplies wiring, consolidates several of the electrical
functions onto one device and improves the reliability of the air conditioner. In addition, the control
board has LED’s that indicate operational status and fault conditions.
1.6 A2 Internal Disconnect
To meet the current U.L. 1995 Safety Standard, the electric heating elements are installed on a separate
electrical circuit. Single phase, 240 volt electric heating elements which exceed 48 amps (12 and 15
kW) require two electrical circuits.
1.7 Electronic Control Board Modes of Operation
Normal
24 VAC power must be continuously applied to “R” and “C”. Upon a call for cooling “Y” and with the
high pressure switch (HPS) closed, the compressor will be energized. (Note: See the delay on make
feature.) The compressor will remain energized during the 3 minute timed low pressure by-pass cycle. If
the low pressure switch (LPS) is open after the 3 minute by-pass cycle, the compressor will de-energize.

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Lock-out
If either of the fault conditions (LPS or HPS) occurs twice during the same call for cooling, the control
board will enter into and indicate the lockout mode. In the lockout mode, the compressor is turned off.
If there is a call for indoor air ow “G”, the blower remains energized, the alarm output is energized and
the status LED will blink to indicate which fault has occurred. When the lockout condition is cleared,
the unit will reset if the demand for the thermostat is removed or when the power is reset. With the
control board, the user can now have either normally closed or normally open contacts by moving a
wire on the control board. ComPac air conditioners are factory wired to be normally open.
Delay on Break
If the compressor is de-energized due to a loss of a cooling “Y” call or the rst fault, the unit re-start
will be delayed 3 minutes from the time the contactor is de-energized. (Note: There is no delay on break
if the lockout condition is reset.)
Delay on Make
On initial power up only, the unit will wait 0.03 to 10 minutes from the cooling “Y” call before
allowing the contactor to energize. The delay can be adjusted by the DOM wheel on the board. Factory
recommended wait is 3 minutes.
Low Pressure By-Pass Time
When starting, the low pressure switch (LPS) fault condition will be by-passed for 3 minutes before
the contactor is de-energized.
Post Purge
Upon a call for indoor airow “G” the blower will energize immediately. When in the cooling mode,
the blower will remain energized for 10 to 90 seconds (adjustable) after the compressor has been de-
energized. The time period can be changed by fan purge wheel on the board. Factory setting is 90 seconds.
LED Indicator Lights
COLOR TYPE STATUS DESCRIPTION
Green Power Contstant On 24 VAC power has been applied
Red Status Contstant On Normal operation
Red Status 1 Blink High pressure switch has opened twice
Red Status 2 Blinks Low pressure switch has opened twice
High Pressure Switch
The high pressure switch is mounted on the compressor liquid line. It is electrically connected to a
lockout relay which shuts down the system if the refrigerant pressure rises to 650 PSIG. This protects
the unit if airow through the condenser is blocked or if the outdoor fan motor fails. Although the
contacts of the high pressure switch close when the refrigerant pressure falls to approximately 450 PSIG,
the system must be manually reset once the lockout relay is activated. A manual reset is necessary to
prevent harmful short-cycling. To reset switch, turn primary power off, then back on or turn thermostat
system switch off, then back on.
Low Pressure Switch
The low pressure switch is mounted on the compressor suction line. It is designed to open if the refrigerant
pressure drops to 40 PSIG; it resets when the pressure rises to 60 PSIG. The switch protects the unit if
airow through the indoor blower is impeded, if the blower motor fails, or if there is a loss of refrigerant.

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LEDs POST PURGE WHEEL DELAY ON MAKE
(COMPRESSOR TIME DELAY) WHEEL
1.8 Electrical Diagrams
The compressor incorporates 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 compressor is energized with a contactor controlled by a 24 VAC pilot signal (see Figure 1). The
evaporator blower motor is cycled by the blower time delay relay.
IMPORTANT
The ModPac incorporates a 90 second purge cycle that runs the evaporator
blower after the thermostat is satised.
To meet the current U.L. 1995 Safety Standard, the electric heating elements are installed on a separate
electrical circuit. Single phase, 240 volt electric heating elements which exceed 48 amps (12 and 15
kW) require two electrical circuits. The compressor and all other motors are on separate electrical circuit
which do not contain any electrical heating elements. The incoming power for units without electric heat
can be wired directly to the unit mounted circuit breaker. The incoming power for units with electric
heat can be wired to the unit mounted terminal block. The external or wall mounted breaker must be
sized for the load of the unit's electrical circuit(s). The required minimum circuit ampacity (MCA)and
maximum fuse size (MFS) for this breaker will be marked on the unit's Data Info in the single point
power entry (SPPE) column.

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Figure 1. Typical Electrical Schematic for Air Conditioners with the PC Board

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Chapter 2. 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.
2.1 Equipment Inspection
Concealed Damage
Inspect all cartons and packages upon receipt for damage in transit. Remove cartons and check for
concealed damage. Important: keep the unit upright at all times. Remove access panels and examine
component parts. (Note: the bottom bracket for Models AVPA20-60 are stored in the condenser air
compartment. Remove a side screen to retrieve them and then replace the side screen). The AVP12 does
not require a bottom bracket. Inspect refrigerant circuit for fractures or breaks. The presence of refrigerant
oil usually indicates a rupture. If damage is apparent, immediately le a claim with the freight carrier.
Units that have been turned on their sides or tops may have concealed damage to compressor motor
mounts or to the oil system. If the unit is not upright, immediately le a claim for concealed damages
and follow these steps:
1. Set unit upright and allow to stand for 24 hours with primary power turned on.
2. Attempt to start the compressor after 24 hours.
3. If the compressor will not start, makes excessive noise, or will not pump, return the unit to the
freight carrier.
2.2 Installation Requirements
General
1. Inspect unit for completeness. Check for missing parts (e.g. hardware). Refer to the installation
kit information in section 2.3.
2. Remove access panels and check for loose wires. Tighten screw connections if necessary.
3. Complete and mail the warranty registration card.
You must consider all of the following when choosing the installation site:
1. Noise: Install the unit so that the least amount of noise will be transmitted to inhabited spaces.
2. Condensate Drainage: Condensate produced during operation must be discharged to a suitable drain.
3. Placement:
A) Place the unit in a shaded area, if possible.
B) Install it above ground for protection against ooding.
C) The unit exhausts air. Be sure that the airow is not impeded by shrubbery or other obstructions.
4. Airow Requirements: Note the minimum CFM requirements (section 2.4). Keep duct lengths as
short as possible. Do not obstruct airow through the unit.
Applications using duct work should be designed and installed in accordance with all applicable safety

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codes and standards. Airxcel Commercial Group strongly recommends referring to the current edition
of the National Fire Protection Association Standards 90A and 90B before designing and installing
duct work. The duct system must be engineered to insure sufcient air ow through the unit to prevent
over-heating of the heater element. This includes proper supply duct sizing, sufcient quantity of
supply registers, and adequate return and lter areas. Duct work must be of correct material and must
be properly insulated. Duct work must be constructed of galvanized steel with a minimum thickness
of .019". Duct work must be rmly attached, secured, and sealed to prevent air leakage. See section
2.4 for additional duct work requirements.
5. Clearances: Note the minimum clearances required for proper operation and service.
MODEL MIN. CLEARANCE AROUND
SIDES (SINGLE UNIT)
MIN. CLEARANCE BETWEEN
UNITS (TWO UNITS)
MIN. SPACE
ABOVE UNIT
12 24 inches (76 cm) 18 inches (46 cm) 24 inches (61 cm)
20/24 30 inches (76 cm) 18 inches (46 cm) 24 inches (61 cm)
30/36 30 inches (76 cm) 18 inches (46 cm) 24 inches (61 cm)
42/48/60 30 inches (76 cm) 30 inches (76 cm) 24 inches (61 cm)
Table 1. Minimum Clearances
6. Codes: Make sure your installation conforms to all applicable electrical, plumbing, building, and
municipal codes. Some codes may limit installation to single story structures.
7. Electrical Supply: The power supply must have the appropriate voltage, phase, and ampacity for the
model selected. Voltage must be maintained above minimum specied values listed below. Refer to
the data sticker on the unit for ampacity requirements.
ELECTRICAL RATING DESIGNATIONS* A C D
Nominal Voltage 208/230 208/230 460
Phase and Hertz 1/60 3/60 3/60
Minimum Voltage 197 187 414
Maximum Voltage 253 253 506
*Letters refer to the system electrical rating in the model number identication. Refer to page 5.
Table 2. Voltage Limitations
8. Ventilation System Set-Up:
Manual Fresh Air System (Conguration N). This is the standard ventilation system in the ModPac
air conditioner. Fresh air ventilation by means of a damper can provide up to 15% of rated air ow
of outside air. The damper has four positions corresponding to 0, 5, 10 and 15% of rated air ow of
outside air. See Figures 3a and 3b.
The damper only opens when the indoor fan is operating. Position the screw on the side of the damper
hood for the desired air ow. Note: the damper on the AVPA12 stays is the same position, regardless
of the operation of the blower.
Motorized Damper - 0 to 450 cfm of Outside Air and Pressure Relief (Conguration B) and manual
dampers, Congurations Z & Y. Note: When setting the manual damper with Conguration
Y, a pathway for the classroom air to exit the room must be provided when setting the damper
position. - Not available on the AVPA12. The settings of the damper require a balometer and a
thermometer for measuring internal and external temperatures.
a.Measure the total supply air with a balometer. If the supply air is controlled by a manual fan
speed controller, make certain that the air ow is in accordance with Table 3, Air Flow (CFM) at
Various Static Pressures. This CFM is referred to as "C" in the illustration and equation below.

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b."A" is the quantity of outside air expressed as a percentage of "C". For example, if the supply air
is 1,220 CFM and 300 CFM of outside air is required, "A" is 25% (300 CFM/1,220 CFM)
Measure the temperature of the outside air.
Multiply the temperature by "A".
c."B" is the quantity of return air expressed as a percentage of "C". "A" and "B" must equal 100%.
Measure the temperature of the indoor return air.
Multiply the temperature of the indoor air by "B".
d.Calculate what the Tmix should be with the desired quantity of outside air.
Measure the actual temperature of Tmix at the inlet to the supply air blower.
Adjust the damper blade until the measured value of the Tmix equals the
calculated or desired value of Tmix. To adjust the damper, loosen the set
screw on the damper rod and move the rod as required. When the adjustment
is complete, tighten the set screw.
The motorized damper, Conguration B, can be controlled by an optional
relay that allows additional external control with a choice of 24, 120 or
240V coils to regulate fresh air ventilation in response to a control located
remote from the air conditioner.
Figure 2. Damper Air Path
2.3 Installation Materials
Installation Kits
All ModPac units have built-in side anges that function as side brackets. All models, except for the
AVPA12, require and are shipped with a bottom mounting bracket. There is also an air intake hood
factory installed behind the lower front panel.

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Standard Kit Components - Models AVPA20-60:
1. One 12 Ga. "L"-shaped bottom bracket (The AVPA12 does not require a bottom bracket.)
Accessories:
The package may include other factory-supplied items (optional) as follows:
Part # Description
50121 Digital thermostat. 1 stage heat, 1 stage cool. Non-programmable. Fan switch: Auto & On.
Manual changeover system switch: Cool-Off-Heat. Low temperature protection. °F or °C.
50123 Digital thermostat. 1 stage heat, 1 stage cool. 7 day programmable. Fan switch: Auto & On.
Auto-change over. Keypad lockout. Non-volatile program memory.
50254 Digital dehumidistat. Required for units with electric reheat.
Note: a humidistat should not be used.
Supply Grilles:
80682 17" x 5" Aluminum, Adjustable Double Deection Supply Grille for the AVPA12
80674 VPG-20S, 20 x 8" Adjustable, Aluminum Double Deection Supply Grille for AVPA 20-24
80675 VPG-30S, 28 x 8" Adjustable, Aluminum, Double Deection Supply Grille for AVPA 30-36
80676 VPG -40S, 30 x 10" Adjustable, Aluminum, Double Deection Supply Grille
for AVPA42-48-60
Return Grilles:
92352 17" x 10" Aluminum Return Grille for the AVPA12
80677 VPG -20R, 20 x 12" Aluminum Return Grille for AVPA 20-24
80678 VPG -30R, 28 x 14" Aluminum Return Grille for AVPA 30-36
80679 VPG -40R, 30 x 16" Aluminum Return Grille for AVPA 42-48-60
Return Filter Grilles:
80683 17" x 10" Aluminum, Return Air Filter Grille for the AVPA12
80671* VPG -20RF, 20 x 12" Aluminum Return Filter Grille for AVPA 20-24
80672* VPG -30RF, 28 x 14" Aluminum Return Filter Grille for AVPA 30-36
80673* VPG -40RF, 30 x 16" Aluminum Return Filter Grille for AVPA 42-48-60
*Use when outside air is not required. Remove and discard lter in unit.
Additional Items Needed:
Additional hardware and miscellaneous supplies (not furnished) are needed for installation. For example,
the list below contains approximate quantities of items typically needed for mounting a unit on a wood
frame wall structure. Concrete or berglass structures have different requirements.
10 3/8" mounting bolts for side brackets. The length needed is typically the wall thickness plus one
inch.
20 3/8" washers
10 3/8" hex nuts
6 3/8" x 2-1/2" lag screws for bottom bracket
•Silicone Sealer to seal around cracks and openings
• 4-conductor low voltage multi-colored wire cable (i.e. thermostat wire)
• Appropriate electrical supplies such as conduit, electrical boxes, ttings, wire connectors,
etc.
• High voltage wire, sized to handle the MCA (minimum circuit ampacity) listed on the data plate.

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• Over-Current Protection Device sized in accordance with the MFS (maximum fuse size) listed
on the unit data plate.
Duct materials usually are also needed in addition to the mounting hardware. To save time, design
the duct work before mounting the unit.
WARNING
FIRE HAZARD
Improper adjustment, alteration, service, maintenance or installation could cause serious
injury, death and/or property damage.
Installation or repairs made by unqualied persons could result in hazards to you and others.
Installation MUST conform with local codes or, in the absence of local codes, with codes of
all governmental authorities have jurisdiction.
The information contained in this manual is intended for use by a qualied 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.
2.4 Porting and Duct Work
General Information
Note: The following instructions are for general guidance only. Due to the wide variety of installation
possibilities, specic instructions will not be given. When in doubt, follow standard and accepted
installation practices, or contact Airxcel Commercial Group for additional assistance.
Wall Openings and Duct Clearance
Measure the dimensions of the supply and return openings on the air conditioner .
WARNING
Cut the supply opening in the exterior wall for the supply and return. IMPORTANT: All
units must have one inch clearance on all four sides of the supply outlet duct ange on
the unit. The one inch clearance must extend on all sides of the supply duct for the rst
three feet from the unit.
Minimum Airow Requirements
WARNING
The duct system must be engineered to assure sufcient air ow through the unit, even
under adverse conditions such as dirty lters, etc. Use Table 2 below and Table 3 - CFM at
External Static Pressure (Wet Coil) in section 5.1.
Ducting
Extensions should be cut ush with the inside wall for applications without duct work.
Applications using duct work should be designed and installed in accordance with the current edition
of the National Fire Protection Association codes and standards 90A and 90B. The duct system must be
engineered to insure sufcient air ow through the unit to prevent over-heating of the heater element.
This includes proper supply duct sizing, sufcient quantity of supply registers, adequate return and lter
area. Duct work must be of correct material and must be properly insulated. Duct must be constructed
of galvanized steel with a minimum thickness of .019" for the rst three feet. Duct work must be rmly
attached, secured and sealed to prevent air leakage. Do not use duct liner on inside of supply duct within
four feet of the unit.

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Galvanized metal duct extensions should be used to simplify connections to duct work and grilles. Use
fabric boots to prevent the transmission of vibration through the duct system. The fabric must be U.L.
rated (UL-181) to a minimum of 197ºF.
Basic Model Maximum Total Static Minimum Filter Area
12 .25 2.25 sq. ft.
24 .40 2.25 sq. ft.
30/36 .40 3.00 sq. ft.
42/48/60 .50 3.90 sq. ft.
Table 3. Maximum Static Pressure
2.5 Fresh Air Hood Installation
The fresh air hood is located on the inside, behind the slots on the bottom front panel. To access the
hood, remove the screws that hold the front panel. The air ow can be adjusted from no (0%) fresh air
to approximately 15% of rated air ow 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.
0% 5% 10 %
15 %
0%
5%
10%
15%
0%
5%
10 %
15 %
Figure 3a. Fresh Air Hood Damper
for AVPA20-60
Figure 3b. Fresh Air Hood Damper
for AVPA12
2.6 Bottom Bracket Installation
1. The ModPac air conditioners have built-in mounting anges. See Figure 4.
2. Refer to Figure 4. Attach the bottom support bracket to the wall using appropriate 3/8" diameter
hardware. Note: The AVPA12 does not require a bottom bracket.
For example, on wooden structures, use 3/8 x 2-1/2 inch all-thread lag screws. The screws must penetrate
the center of the wall stud. Drill a pilot hole in the stud to prevent it from splitting.

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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 4. Wall Mounting Detail - Models AVPA12-60
2.7 Mounting the Unit
1. For wiring into the back of unit, locate the lower of the two knock-outs on the wall side of the
unit. Drill a one inch hole in the shelter wall to match this opening. Allow sufcient clearance to
run 3/4" conduit through the hole and to the unit.
2. Apply a generous bead of silicone sealer on the wall side of the mounting brackets on the unit.
Circle the mounting holes with the silicone bead.
3. Using an appropriate and safe lifting device, set the unit on the bottom support bracket mounted
on the wall. You must stabilize the unit on the bracket with the lifting device or by some other
means - the bracket alone is not sufcient. The AVPA12 does not require a bracket.
4. Make sure that the duct anges are properly aligned with the wall opening. Adjust as necessary.
5. Note the holes in each side bracket. Using the holes for guides, drill holes through the wall with a
3/8" drill bit. Insert the 3/8 x 5" bolts through the brackets. Install nuts and washers on the inside
of the building. Tighten the bolts to secure the unit.
6. Apply a bead of silicone where the ashing and side brackets contact the unit and the building wall.
7. Fasten the ashing to the unit casing and the building wall using #10 x 1/2 inch sheet metal screws.

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8. On the inside of the building, install the wall sleeves in the supply and return air openings. The
sleeves may be trimmed to t ush with the inside wall. 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.
9. Check the t of each sleeve to its mating ange for possible air leaks. Apply silicone sealer to
close any gaps. Install the air return and supply grilles.
WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow safety warnings exactly could result in serious injury, death, and/or property
damage.
Turn off electrical power at fuse box or service panel BEFORE making any electrical
connections and ensure a proper ground connection is made before connecting line voltage.
2.8 Electrical Connections
IMPORTANT!
All electrical work must meet the requirements of local codes and ordinances. Work should be
done only by qualied persons.
CAUTION
These air conditioners incorporate an internal crankcase heater for compressor protection.
The crankcase heater must be energized for at least 24 hours prior to starting the compressor.
ModPac air conditioners may be ordered with a scroll compressor. Scroll compressors, like several other
types of compressors, will only compress in one rotational direction. The direction of rotation is not an
issue with single-phase compressors since they will always start and run in the proper direction. However,
three phase compressors will rotate in either direction depending upon phasing of power. Since there
is a 50-50 chance of connecting power in such a way as to cause rotation in the reverse direction, it is
imperative to conrm that the compressor is rotating in the proper direction at the initial eld start-up
of the system. Verication 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 verication for
self contained system with small critical refrigerant charges, where 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.
There is no negative impact on durability caused by operating three phase compressors in the reversed
direction for a short duration of time, usually dened as less than one hour. However, after several
minutes of operation the compressor's internal protector will trip. The compressor will then cycle on the
protector until the phasing is corrected. Reverse operation for longer than one hour may have a negative
impact on the bearings. Failure to ensure proper rotation will void the warranty of the compressor.
To change the rotation, turn off power to the unit and swap L1 and L2 at the disconnect or circuit breaker.
High Voltage Wiring
The power supply should have the proper voltage, phase, and ampacity for the selected model.

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1. Refer to the electrical data on the data sticker on the unit for eld wiring requirements of the unit.
Size the incoming power supply lines and the fuse(s) or HACR breaker(s) according to requirements
described in the National Electric Code. Run the power conductors through the knockouts on the
side or back of the unit. Use appropriate conduit and strain reliefs.
CAUTION
CAUTION! This system contains components that require phasing for correct rotation.
Failure to observe rotation and correct on start-up will cause damage not covered by the
Airxcel Commercial Group Limited Product Warranty.
2. Connect the wires to the input side of the internal breaker (L1 & L2 for single-phase units; L1,
L2, & L3 for three phase models).
CAUTION
Note: Power supply service must be within allowable range (+10% - 5%) of rated voltage
stamped on the unit rating plate. To operate nominal 230/208V unit at 208V, change the
transformer line tap from 240V to 208V following the instruction on wiring label in unit.
3. Install the ground wire on the ground lug.
4. Units designed to operate on 460V have a step down transformer for 230V motors.
Low Voltage Wiring
1. Pull the low voltage wiring (e.g., Class 2 thermostat wire) from the air conditioner into the
thermostat / sub-base assembly.
2. Mount the sub-base on a level plane. Use a spirit level. Connect the thermostat wire to the terminal
board and the thermostat as shown in Figure 6.
3. Attach the thermostat assembly to the sub-base. Check the heat anticipator settings - it should
read .40.
THE INTERNAL TRANSFORMER IS NOT DESIGNED TO POWER OTHER
EXTERNAL DEVICES.

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SIMPLE COMFORT THERMOSTAT CONNECTION DIAGRAM
for Marvair Heat Pumps and Air Conditioners (without hot gas reheat or electric heat)
Figure 5. Thermostat Connection Diagram

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Chapter 3. Start-Up
IMPORTANT
If your unit has a crankcase heater be sure that the crankcase heater has been energized for
at least 24 hours prior to start-up of the unit. Double check all electrical connections before
applying power. Various thermostats can be used to control the air conditioner. The thermostat
may have a fan switch with an Automatic and On positions, a system switch with Heat, Cool,
and Off positions. The product data sheets have detailed description of the various Marvair
thermostats. Since other thermostats or remote control systems may be used, the following
procedures should be viewed as guidelines for standard thermostats with system and fan
switches.
3.1 Check-Out of Cooling Cycle
Procedure:
1. Set the cooling temperature set point on the wall thermostat to a point higher than the ambient
temperature. Set the heating temperature set point to a temperature that is lower than the
ambient.
2. Set the thermostat system switch in the AUTO position. Nothing should operate at this time.
3. For units with the PC board, set the time delay in the control box to 3 minutes.
4. Slowly lower the thermostat's cooling temperature set point until the switch closes. The
indoor fan should operate.
Once the indoor fan turns on, allow approximately three minutes for the compressor to
start. Note that the outdoor fan may not come on immediately, because it is cycled by
refrigerant pressures.
IMPORTANT
Alternately, when outdoor conditions are lower than the set point, a source of heat such as
a hair dryer can be directed on the air temperature sensor to simulate warmer conditions,
which will bring on mechanical cooling and start the compressor.
5. To stop cooling, slowly raise the thermostat cooling set point to a temperature higher than
the ambient.
If the unit fails to operate, refer to the troubleshooting information in Chapter 4.
Follow the same procedure for additional units.
NOTE: Blower Time Delay Relay (BTR) and the Fan Purge mode (PC board units) allows
the indoor fan to run for approximately 90 seconds after the compressor is off. This operation
provides a small improvement in system efciency.
3.2 Check-Out of Heating Cycle
Procedure: (Applies only to units with resistance elements.)
1. Raise the heating temperature set point 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.