Airxcel Marvair ComPac II Series User manual

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Description .........................................5
Installation........................................22
Start-Up.............................................39
Troubleshooting..............................41
Parts List ..........................................44
Maintenance ....................................47
Warranty ...........................................48
ComPac®I and ComPac®II
Air Conditioner Product Manual
VerticalWall-MountAirConditioners
with Front Control Box Panel
Models AVP20-24-30-36-42-48-60-72
P/81024 9/04-12
supersedes 11/03-11
Manufactured By:
Marvair®Division of AIRXCEL®, Inc.
P.O. Box 400 • Cordele, Georgia 31010
156 Seedling Drive • Cordele, Georgia 31015
[phone] • Fax [phone]
E-mail:[email protected] •Internet:www.marvair.com

2ComPac 9/04-12
How To Use
This Manual
This manual is intended to be a guide to Marvair's ComPac®line of vertical air conditioners. It
contains installation, troubleshooting, maintenance, warranty, and application information. The
informationcontainedinthismanualistobeusedbytheinstallerasaguideonly. Thismanual does
not supersede or circumvent any applicable national or local codes.
If you are installing the ComPac®unit, first 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 ComPac®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.
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 BUILD-
ING CODES & 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
© 9/04 Marvair®Div. Airxcel®, Inc.
Important
Safety
Precautions
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE.

3ComPac 9/04-12
ComPac®A/CDescription&Specifications
1.1 GeneralDescription ........................................................................................ 5
1.2 ModelIdentification ........................................................................................ 5
1.3 SerialNumberDateCode............................................................................... 5
1.4 RatingsandSpecifications ............................................................................... 6
1.5 GeneralOperation .......................................................................................... 9
1.6a ElectronicControlBoardModeofOperation ................................................ 10
1.6b MechnicalControls ....................................................................................... 12
1.7 OptionalControls ......................................................................................... 12
1.8 ElectricalDiagrams ....................................................................................... 14
1.9 EconomizerComponents .............................................................................. 21
Installation
2.1 EquipmentInspection .................................................................................... 23
2.2 InstallationRequirements ............................................................................... 23
2.3 InstallationMaterials ..................................................................................... 24
2.4 PortingandDuctWork ................................................................................. 26
2.5 FreshAirHoodInstallation ........................................................................... 27
2.6 BracketInstallation ....................................................................................... 27
2.7 MountingtheUnit ......................................................................................... 27
2.8 ElectricalConnections ................................................................................... 28
Start-Up
3.1 Check-OutofCoolingCycle......................................................................... 33
3.2 Check-OutofHeatingCycle ......................................................................... 33
3.3 A/CTestingwithLL357D2........................................................................... 34
Troubleshooting
4.1 Overview...................................................................................................... 35
4.2 FailureSymptomsGuide ............................................................................... 36
4.3 CompressorTroubleshooting ........................................................................ 37
4.4 ControlBoardDiagnosis ............................................................................... 38
PartsList
5.1 PartsList ...................................................................................................... 39
5.2 Illustrations ................................................................................................... 40
Maintenance
6.1 ScheduledMaintenance ................................................................................ 42
Warranty
7.1 LimitedProductWarranty ............................................................................. 43
7.2 OptionalSilverServiceProgram.................................................................... 44
TABLE OF
CONTENTS

4ComPac 9/04-12
ILLUSTRATIONS Figure 1a. ComPac®I& II A/C Dimensions-Models 20-36 ....................... 7
1b. ComPac®I&IIA/CDimensions -Models 42-60 ........................ 7
1c. ComPac®I&IIA/CDimensions-Model72 ............................... 8
Figure 2. RefrigerantCircuit ......................................................................... 9
Figure 3a. TypicalElectricalSchematic-ComPac®IA/CModels20-60
withMechanicalRelaysandContactors....................................... 15
3b. TypicalElectricalSchematic-ComPac®IA/CModels20-60
withElectronicControlBoard ..................................................... 16
3c. TypicalElectricalSchematic-ComPac®IIA/CModels20-60
withMechanicalRelaysandContactors....................................... 17
3d. TypicalElectricalSchematic-ComPac®IIA/CModels20-60
withElectronicControlBoard ..................................................... 18
3e. TypicalElectricalSchematic-ComPac®IA/CModel72 .............. 19
3f. TypicalElectricalSchematic-ComPac®IIA/CModel72............. 20
Figure 4. H205ATemperatureControlPoints ............................................ 21
Figure 5. H205AControlPointAdjustment ............................................... 22
Figure 6. FreshAirHoodInstallation ......................................................... 27
Figure 7. WallMountingDetail-ComPac®A/CAVP20-72 ...................... 28
Figure 8a. ThermostatWiringDetails ........................................................... 31
Figure 8b. CommStat3™WiringDetail ...................................................... 31
Figure 8c. LL357D2WiringDetail .............................................................. 32
Table 1 CFM@ExternalStaticPressure .................................................. 6
Table 2 ShipWeight .................................................................................. 6
Table 3 StandardFilterSize....................................................................... 6
Table 4 MinimumClearances................................................................... 24
Table 5 VoltageLimitations ..................................................................... 24
Table 6 MaximumStaticPressure ............................................................ 26
TABLES

5ComPac 9/04-12
Marvair'sComPac®linesareaseriesofverticalwall-mountedairconditioningsystemsthat
provideheating,cooling,andventilationforelectronicequipmentshelters,processcontrol
centers, andotherapplicationswithhighinternalheatgains. Theseriesincludesmultiple
sizesandnominalcoolingcapacitiesfrom18,000to72,000BTUH. Resistanceheating
elementsareavailableinvariouswattages.
Marvair’sComPac®I&ComPac®IIairconditioners,modelsAVP20-60,featurean
exclusiveelectroniccontrolboard.Thecontrolboardconsolidatesseveraloftheelectrical
componentsandimprovestheairconditioner’sreliability.Thecontrolboardreplacesthe
blowerrelay,thelockoutrelay,thecompressortimedelayandthetimedlowpressure
bypass.Inaddition,thecontrolboardhasLED’stoindicateoperatingstatusandfault
conditionstoassisttheservicetechnician.Acompletedescriptionoffunctionsofthe
controlboardisinSection1.6. TheAVP72doesnotcurrentlyhavethecontrolboard.
TheComPac®I&ComPac®IImodelsaredesignedforeasyinstallationandservice. Major
componentsareaccessibleforservicebeneathexternalpanels.
Allunitshaveinternaldisconnects(optionalon460V). Dependinguponstateandlocalcode
requirements,thisfeaturemayeliminatetheneedforanexternalbreakerordisconnect.
TheComPac®IA/Chasa0-15%manualoutsideairdamperandtheComPac®IIA/Chas
afactoryinstalledeconomizerfor100%freecoolingwithoutsideair.
DESCRIPTION &
SPECIFICATIONS
1.1 GENERAL
DESCRIPTION
1.2 MODEL
IDENTIFICATION
Themodelidentificationnumberisfoundonthedatasticker. Ratingplatelocatedonside
panel.
1.3 SERIAL NUMBER
DATE CODE
AVP ** AC * * * *
AirSource VerticalPackage
*Ratings at 60 Hz.
Power Supply
A = 208/230V, 1ø, 60 Hz F = 220V, 1ø, 50 Hz L = 208/2300V, 1ø, 60 Hz
C = 208/230V, 3ø, 60 Hz G = 220V, 3ø, 50 Hz & 200V, 1ø, 50 Hz
D = 460V, 3ø, 60 Hz H = 380V, 3ø, 60 Hz M = 200V, 1ø, 50 Hz
E = 380V, 3ø, 50 Hz J = 460V, 3ø, 50 Hz
Electric Heat (kW)
00, 04, 05, 06, 08, 09, 10, 15
Configuration
N=ComPac®IA/C
C=ComPac®IIA/C
System Type = Air Conditioner
NominalCooling*
20= 18,000 BTUH 42= 41,500BTUH
24= 24,000 BTUH 48= 48,000BTUH
30= 29,400 BTUH 60= 57,000BTUH
36= 35,600 BTUH 72= 72,000BTUH
A = January E=May J = September L = 2000 R = 2004 V = 2008
B = February F = June K = October M = 2001 S = 2005 W = 2009
C = March G = July L = November N = 2002 T = 2006
D = April H = August M = December P = 2003 U = 2007
Special Option Code
R = Electric Reheat
U = Scroll Compressor

6ComPac 9/04-12
1.4 RATINGS &
SPECIFICATIONS
Table 1. CFM @ External Static Pressure (Wet Coil) (IWG)
Table 2. Ship Weight
Table 3. Filter Size
* Two filters required.
MODEL 0.10 0.20 0.25 0.30 0.40 0.50
20 860 810 740 670
24 860 810 740 670
30 1100 1000 960 920 810
36 1310 1220 1185 1150 1060
42 1650 1585 1520 1450 1360
48 1900 1830 1760 1700 1620
60 1900 1830 1760 1700 1620
72 2100 1950 1800 1730 1660
20/24 30/36 42 48 60 72
MODEL LBS/KG LBS/KG LBS/KG LBS/KG LBS/KG LBS/KG
COMPAC®I A/C 274/125 355/160 495/225 521/240 535/245 600/272
COMPAC®II A/C 286/130 365/170 527/240 552/250 565/260 640/290
MODEL 20/24 30/36 42/48/60 72
FILTER SIZE (inches) 16 x 25 x 2 16 x 30 x 2 22 x 36-1/2 x 2 18 x 24 x 2*
FILTER SIZE (mm) 406 x 635 x 51 406 x 762 x 51 559 x 927 x 51 452 x 610 x 51

7ComPac 9/04-12
Figure 1b. ComPac®I A/C & ComPac®II A/C Dimensions- Models AVP42-60 (in inches)
Figure 1a. ComPac®I & ComPac®II A/C Dimensions- Models AVP20-36 (in inches)
NOTE: Dimensional tolerance ± 1/16"
NOTE: Dimensional tolerance ± 1/16"
DISCONNECT
ACCESS
J
K
C
FRONT VIEW
M
OUTSIDE AIR HOOD
B
R.H. SIDE VIEW BACK VIEW
P
O
A
2.0"
51 mm
34-1/2"
876 mm
18-1/2"
470 mm
50-3/4"
1289 mm
HEATER
ACCESS
L
67.0"
1702 mm
N
SUPPLY AIR
OPENING
H
RETURN AIR
OPENING
F
E
D
G
MOUNTING HOLES
CTR TO CTR
2.0"/
51 mm
2.0"/
51 mm
I
AIR INLET
SLOTS IN
CII ONLY
K.O.'s**
K.O.'s**
AIR OUTLET
2.0"/51 mm
2.0"/
51 mm
H
3/4" (19 mm)
I.D. DRAIN
(9 PLC'S)
BOTTOM MTG. BRKT.
W/MTG. HOLE LOCATIONS
4-9/16”
AA AA
BB
3-9/16” (90 mm)
(116 mm)
1-1/16” (27 mm)
3/8” (10 mm)
TM
E
SUPPLY AIR OPENING
RETURN AIR OPENING
2.0"
51 mm
6.0"
152
mm
24.0"
610
mm
42.0"
1067
mm
60.0"
1524
mm
78.0"
1981
mm
FRESH AIR HOOD
1.5"/38
mm
K.O.'S*
2.0" 51 mm
MOUNTING HOLES CTR. TO CTR.
HEATER
ACCESS
COVER
DISCONNECT
ACCESS
COVER
FRONT VIEW R.H. SIDE VIEW BACK VIEW
FLANGE WIDTH
3/4" (19 mm)
I.D. DRAIN
AB
C
D
E
F
G
H
H
I
JK
L
M
NO
P
SLOTS IN
CII ONLY**
Q
R
3/8" (10 mm) SQ (10 PLC'S)
K.O.'S*
AIR
OUTLET AIR
INLET
BOTTOM MTG. BRKT.
W/MTG. HOLE LOCATIONS
1-5/8”(41 mm)
4-3/4”
(121 mm)
3-7/8”(98 mm) 19-3/4”
(502 mm) 19-3/4”
(502 mm) (6 PLC'S)
3/8”(10 mm)
41”(1041 mm)
TM
30"
762 mm
30 x 10"(762 x 254 mm)
30 x 16"(762 x 406 mm)
MODELABCDEFGH I JKLMNOPQR
42/48/60 45 22-5/8 86 10 30 16 26-1/2 30 1-5/16 40-9/16 38-9/16 1-1/8 43-1/2 32-3/8 30-3/8 1-1/4 83-5/16 1-3/4
MODEL A B C D E F G H I J K L M N O P AA BB
20/24 39-1/2 17-1/4 71-1/2 8 20-1/2 12 27-11/16 20 3-3/4 36-5/16 1-11/16 7/8 38 27-11/16 26 3-5/8 17-5/8 35-1/4
30/36 44-9/16 17-1/4 71-1/2 8 18 14 28-7/16 28 3-3/4 36-5/16 1-11/16 7/8 43-1/8 27-11/16 26 3-5/8 20-1/4 40-1/2

8ComPac 9/04-12
Figure 1c. ComPac®I A/C & ComPac®II A/C Dimensions- Models AVP72 (in inches & mm)
SLOTS IN
COMPAC®II ONLY
SLOTS IN
COMPAC®II ONLY

9ComPac 9/04-12
RefrigerantCycle(CoolingMode)
The ComPac®I & ComPac®II A/C use R-22 refrigerant in a conventional vapor-
compressionrefrigerationcycletotransferheatfromairinanenclosedspacetotheoutside.
Adoubleblowerassemblyblowsindoorairacrosstheevaporator. Coldliquidrefrigerant
passingthroughtheevaporatorisboiledintogasbyheatremovedfromtheair.Thewarmed
refrigerantgasentersthecompressorwhereitstemperatureandpressureareincreased.The
hotrefrigerantgascondensestoliquidasheatistransferredtooutdoorairdrawnacrossthe
condenserbythecondenserfan. Liquidrefrigerantismeteredintotheevaporatorthrough
capillarytubestorepeatthecycle.
Heating Mode
A wall-mountedthermostatcontrolstheheatingcycleofmodelswhichincorporateresistance
heatingelements. Onacallforheat,thethermostatclosestheheatrelaytoenergizetheindoor
fanandtheresistanceelements. Exceptonunitswiththeoptionaldehumidificationkit, the
compressorislockedoutduringtheheatingcycle.
EconomizerOperation(ComPac®IIA/COnly)
Theeconomizerisaregulateddampersystemwithcontrols. Thedamperregulatesthe
circulationofoutsideairintotheenclosure(whentheoutdoorairconditionsaresuitable)to
reducetheneedformechanicalcooling,saveenergy,andextendcompressorlife.
Dependingupontheoptionsselected,thedamperrespondstotheenthalpyoftheoutdoorair.
Onacallforcoolingfromaspacethermostat,itoperatesasfollows:
When the enthalpy of the outdoor air is below the set point, the outdoor air damper is
proportionedopen(andreturnairdamperisproportionedclosed)tomaintainbetween50°F
and56°Fatthemixed/dischargeairsensor.
Whentheenthalpyoftheoutdoorairisabovethesetpoint,theoutdoorairdamperclosesto
itsminimumposition. Acallforcoolingfromthespacethermostatbringsonmechanical
cooling.
Anoptionalbuilt-inadjustableminimumpositionpotentiometer(partnumber70012)controls
theamountofoutdoorairadmittedtomeetminimumventilationrequirements.
1.5 GENERAL
OPERATION
Figure 2. Refrigerant Circuit
Evaporator (Indoor Coil)
Distributor &
Capillary
Tubes
Filter
Drier
Twin Blowers
Discharge Line
Condenser Fan
Condenser (Outdoor Coil)
Suction
Line
Compressor

10 ComPac 9/04-12
Normal
24VACpowermustbecontinuouslyappliedto“R”and“C”.Uponacallforcooling“Y”and
withthehighpressureswitch(HPS)closed,thecompressorwillbeenergized.(Note:Seethe
delayonmakefeature.) Thecompressorwillremainenergizedduringthe3minutetimedlow
pressureby-passcycle,ifthelowpressureswitch(LPS)isopenthecompressorwillde-
energize.
Lock-out
Ifeitherofthefaultconditions(LPSorHPS)occurstwice,thecontrolboardwillenterinto
andindicatethelockoutmode.Inthelockoutmode,thecompressoristurnedoff.Ifthereis
acallforindoorairflow“G”,theblowerremainsenergized,thealarmoutputisenergizedand
thestatusledwillblinktoindicatewhichfaulthasoccurred. Whenthelockoutconditionis
cleared,theunitwillresetifthedemandforthethermostatisremovedorwhenthepoweris
reset.Withthecontrolboard,theusercannowhavenormallyclosedcontactsbymovinga
wireonthecontrolboard.TheComPac®airconditionersarefactorywiredtobenormally
open.
Delay on Break
Ifthecompressorisde-energizedduetoalossofacooling“Y”callorthefirstfault,theunit
re-startwillbedelayed3minutesfromthetimethecontactorisde-energized. (Note:There
isnodelayonbreakifthelockoutconditionisreset.)
Delay on Make
Oninitialpoweruponly,theunitwillwait0.03to10minutesfromthecooling“Y”callbefore
allowingthecontactortoenergize.ThedelaycanbeadjustedbytheDOMwheelonthe
board.Factoryrecommendedwaitis3minutes.
LowPressureBy-PassTime
Whilerunningorstarting,thelowpressureswitch(LPS)faultconditionwillbeby-passed
for3minutesbeforede-energizingthecontactor.
PostPurge
Uponacallforindoorairflow“G”theblowerwillenergizeimmediately. Wheninthecooling
mode,theblowerwillremainenergizedfor10to90seconds(adjustable)afterthecompressor
hasbeende-energized.Thetimeperiodcanbechangedbyfanpurgewheelontheboard.
Factorysettingis90seconds.
LEDIndicatorLights
COLOR TYPE STATUS DESCRIPTION
Green Power Constant On 24 VAC power has been applied
Constant On Normaloperation
1Blink High pressure switch has opened twice
Red Status 2 Blinks Low pressure switch has opened twice
1.6AELECTRONIC
CONTROL BOARD
MODE OF
OPERATION
(AVP20-60)
(SEE SECTION 1.6B
FOR MECHANICAL
CONTROLS)

11 ComPac 9/04-12
LowAmbientControl
Thelowambientcontrol permitscoolingwhenoutdoorambienttemperaturesarelow. The
controlusesareverse-actinghighpressureswitchtocyclethecondenserfanmotoraccording
toliquidrefrigerantpressureconditions. Switchclosureandfanoperationoccurs whenthe
pressurereaches250PSIG.Theswitchopensagainwhentherefrigerantpressurefallsto190
PSIG. Therefore, the outdoor fan always starts after the compressor, and it will cycle
frequentlyduringnormaloperationatlowoutdoorconditions.
HighPressureSwitch
Thehigh pressureswitchismountedonthecompressordischargeline.Itis electrically
connectedtoalockoutrelaywhichshutsdownthesystemiftherefrigerantpressurerisesto
400 PSIG (AVP60 setting is 450 PSIG). This protects the unit if airflow through the
condenserisblockedoriftheoutdoorfanmotorfails.
Althoughthecontactsofthehighpressureswitchclosewhentherefrigerantpressurefallsto
approximately 300 PSIG, the system must be manually reset once the lockout relay is
activated. Amanualresetisnecessarytopreventharmfulshort-cycling. Toresetswitch,turn
primarypoweroff,thenbackonorturnthermostatsystemswitchoff,thenbackon.
LowPressureSwitch
Thelowpressureswitchismountedonthecompressorsuctionline. Itisdesignedtoopen
iftherefrigerantpressuredropsto35PSIG; itresetswhenthepressurerisesto60PSIG.
Theswitchprotectstheunitifairflowthroughtheindoorblowerisimpeded,iftheblower
motorfails,orifthereisalossofrefrigerant.
LEDs
POST PURGE
WHEEL DELAY ON MAKE
(COMPRESSOR TIME DELAY)
WHEEL
MOVE WIRE FROM NORMALLY OPENTERMINAL TO
NORMALLY CLOSED IF NORMALLY CLOSED IS DESIRED

12 ComPac 9/04-12
TimeDelay/Anti-ShortCycleTimer
Thetimedelay(delayonmake)preventsthecompressorfromrestartingimmediatelyafter
interruptionofpower. Thedelayinterval,whichisadjustablefrom.2to10minutes(factory
set at 3 minutes), protects the compressor by allowing internal refrigerant pressures to
equalize. Fordualunits,setonetimerat3minutesandtheotherat5minutes.
Thetimedelaydoesnoteffecttheelectricheatcircuit.
LowAmbientControl
Thelowambientcontrol permitscoolingwhenoutdoorambienttemperaturesarelow. The
controlusesareverse-actinghighpressureswitchtocyclethecondenserfanmotoraccording
toliquidrefrigerantpressureconditions. Switchclosureandfanoperationoccurs whenthe
pressurereaches250PSIG.Theswitchopensagainwhentherefrigerantpressurefallsto190
PSIG. Therefore, the outdoor fan always starts after the compressor, and it will cycle
frequentlyduringnormaloperationatlowoutdoorconditions.
HighPressureSwitch
Thehigh pressureswitchismountedonthecompressordischargeline.Itis electrically
connectedtoalockoutrelaywhichshutsdownthesystemiftherefrigerantpressurerisesto
400PSIG. Thisprotectstheunit ifairflowthroughthecondenserisblockedoriftheoutdoor
fanmotorfails.
Althoughthecontactsofthehighpressureswitchclosewhentherefrigerantpressurefallsto
approximately 300 PSIG, the system must be manually reset once the lockout relay is
activated. Amanualresetisnecessarytopreventharmfulshort-cycling. Toresetswitch,turn
primarypoweroff,thenbackonorturnthermostatsystemswitchoff,thenbackon.
LowPressureSwitch
Thelowpressureswitchismountedonthecompressorsuctionline. Itisdesignedtoopen
iftherefrigerantpressuredropsto35PSIG; itresetswhenthepressurerisesto60PSIG.
Theswitchprotectstheunitifairflowthroughtheindoorblowerisimpeded,iftheblower
motorfails,orifthereisalossofrefrigerant.
Lock-OutRelay
Thelockoutrelaypreventstheunitfromcyclingonthepressureswitchbyprovidingpositive
shutdownifthehighpressurelimitisexceeded. Anextrasetofdrycontacts(normallyopen)
ontherelay(Figure8)maybeusedforsignalingalockoutcondition. Oncetriggered,therelay
mustbemanuallyreset.
TimedLowPressureBy-Pass
Thetimedsafetybypassprovidesacurrentpatharoundthelowpressureswitchfollowing
each start for a period of one to three minutes. This bypass is essential when operating
mechanicalcoolingwhenambienttemperaturesarelessthan20°F(-6°C).
HardStartKit
Usedonsinglephaseequipmenttogivethecompressorhigherstartingtorqueunderlow
voltageconditions.Generallynotrecommendedonunitswithscrollcompressors.
ExtremeDutyPackage
The Extreme Duty Package allows selected Marvair®ComPac®I & ComPac®II air
conditionerstooperateinextremelycoldandhotambientconditions.TheExtremeDutyKit
1.6BMECHANICAL
CONTROLS
(AVP20-72)
1.7 OPTIONAL
CONTROLS &
PACKAGES

13 ComPac 9/04-12
isalwaysfactoryinstalledandisavailableonallComPac®airconditioners.ComPac®Iair
conditioners (non-economizer units) will operate from 0°F to 130°F (-18°to 54°C).
ComPac®IIairconditioners(economizerunits)willoperatefrom-20°Fto130°F(-29°to
54°C).
TheExtremeDutyPackageincludesasuctionlineaccumulator,thermalexpansionvalve
(TXV),crankcaseheater,hardstartkit,anautoreset,adjustablehighpressureswitchandan
outdoorthermostatandfancycleswitch. ThefancyclecontrolisstandardonallComPac®
airconditionersandoperatesbasedupontheliquidlinepressure.Theoutsidethermostat
openswhenevertheoutsidetemperatureisbelow50°F(10°C)andcloseswhentheoutside
temperatureis50°F(10°C)orhigher.Wheneverthetemperatureisbelow50°F(10°C),the
fancycleswitchisinthecircuit;whentemperaturesare50°F(10°C)orhigher,thefancycle
switchisnotinthecircuit.TheoutdoorthermostatisusedwithaTXVtopreventexcessive
cyclingor"hunting"oftheTXV.
CoastalEnvironmental (ComPac®IA/COnly)
Recommendedforunitstobeinstallednearanoceanoronseacoast.Includesstainlesssteel
fasteners,sealedcondenserfanmotor,sealedcontrolbox,protectivecoatingappliedtoall
exposedinternalcopperinthecondensersectionandaphenolicorimpregnatedpolyurethane
coatingonthecondensercoil.
StainlessSteelCabinet(ComPac®IA/COnly)
Allsheetmetalconstructedofstainlesssteel.
HotGasBypass (ComPac®IA/COnly)
Usedinspecialtyapplications;i.e.,MagneticResonanceImaging(MRI)buildings,toprevent
magneticvoltagedisturbancecausedbycompressorcycling. Twohotgasbypassoption
packagesareavailabletoallowoperationto20°F(-7°C)orminus20°F(-29°C). Please
refertoHotGasBypassApplicationBulletinfordetails.
ElectricReheatDehumidification
Ahumiditycontroller(p/n50057)allowselectricheatandcoolingtooperatesimultaneously.
Marvair®airconditionersequippedwiththedehumidificationoptionallowtheindoorhumidity
ofthecontrolledenvironmenttobemaintainedatorbelowacertainhumiditysetpoint.These
unitsdonothavetheabilitytoaddhumiditytothebuilding.
IMPORTANT:Theelectricalwireandbreakerorfusesmustbesizedforsimulta-
neous operation of the electric heater and the air conditioner. Refer to the data
stickerontheunitortheComPac®AirConditionerProductDataSheetforthesizing
information.
Dehumidificationisachievedbyoperatingmechanicalcoolinginconjunctionwithelectricreheat.
Thestripheatissizedapproximatelytothesensiblecapacityofthetotaltonnageofthemachine(i.e.,
ona24,000BTUunitthestripheatissizedatapproximately20,000BTU).Becausethestripheat
issizedtotheapproximatesensiblecoolingcapacity,onlyselectedmodelsareavailable.
Operation:
Whenthehumidityrisesabovethesetpointonthehumiditycontrollerbothmechanicalcooling
andelectricreheatoperatetotempertheairandlowerthehumidity.Ifthetemperatureinthe
controlledenvironmentrisesabovethesetpointofthethermostatandtheunitisoperatingin

14 ComPac 9/04-12
thedehumidificationmode,thecallforcoolingwilloverridethecallfordehumidificationand
thestripheatisdisengageduntilthethermostatissatisfied.Thisassurestheenvironment
temperatureismaintainedasfirstpriorityandhumiditycontrolissecond.
Inapplicationswhereashelterhasredundantairconditioningunitsandiscontrolledbyalead
lagcontroller(Marvair'sLL357D2orCommStat3™Controller),mosttimesthedehumidi-
ficationoptionisonlynecessaryonone of the two units. It is possible for one unit to be
operatinginthecoolingmodewhiletheunitwithdehumidificationisoperatingatthesametime.
If the cooling unit does not maintain the shelter temperature set point, the unit with
dehumidificationwillgointothecoolingmode.Itdoesnotmatterwhethertheunitwith
dehumidificationistheleadorlagunit.
ThreePhase VoltageMonitor, Marvair®P/N 51394
Continuouslymeasuresthevoltageofeachofthethreephases.Themonitorseparatelysenses
lowandhighvoltage,voltageunbalanceincludingphaselossandphasereversal.AnLED
indicatorglowswhenallvoltagesareacceptable.Automaticallyresetswhenvoltagesand
phasesarewithinoperatingtolerances.
DirtyFilterIndicators
TwotypesofdirtyfilterindicatorsareavailablefromMarvair®.Aflagtypedetectsareduction
ofairflowonthedischargesideofthefilter.Whenareductioninairflowisdetected,asignal
issenttoasetofdrycontacts.Formorereliable,preciseindicationofadirtyfilter,adiaphem
typeofindicatorshouldbeused.Thistypemeasurestheairpressureoneithersideofthefilter
andwhenthepressuredropsbelowthesetpoint,asignalissenttoasetofdrycontacts.The
setpointisadjustable.
MinimumPotentialPotentiometer
Usedin theComPac®IIunits withthefactory installedeconomizer.The potentiometer
preventstheeconomizerfromclosingcompletely,assuringthatoutsideairwillbebroughtinto
theshelterandexhaustedwhenevertheindoorblowerisoperating.Thisprovidesposition
pressurizationofthebuilding.Theminimumpotentialpotentiometerisadjustable.
Thecompressorandcondenserfanareenergizedwithacontactorcontrolledbya24VAC
pilotsignal.
SomecompressorsincorporateaninternalPTCcrankcaseheaterthatfunctionsaslongas
primarypowerisavailable. Theheaterdrivesliquidrefrigerantfromthecrankcaseand
preventslossoflubricationcausedbyoildilution. Powermustbeappliedtotheunitfor24
hoursbeforestartingthecompressor.
Thecondenser(outsidefan)motorisenergizedbythesamecontactor. However,the motor
iscycledonandoffbythelowambientcontrol(seelowambientcontrol1.6aand1.6b).
Theindoorevaporatorfanmotoriscycledbytheblowertimeddelayrelay.
1.8 ELECTRICAL
DIAGRAMS

15 ComPac 9/04-12
5
TRANSFORMER
NOTE 1
GENERAL NOTES:
1. 208/230 VOLT 60 HZ, 1 PH POWER SUPPLY. SEE DATA PLATE FOR AMPACITY & FUSE SIZE.
DISCONNECT SHOWN.
2. SPEED TAP FOR MULTISPEED MOTORS - SEE MOTOR NAMEPLATE FOR WIRE COLOR.
3. TRANSFORMER IS FACTORY WIRED FOR 230 VOLT OPERATION. FOR LOWER VOLTAGES,
INTERCHANGE ORANGE AND RED LEADS. INSULATE UNUSED LEADS.
4. OPTIONAL CRANKCASE HEATER SHOWN. STANDARD ON RECIPROCATING COMPRESSORS.
NOTE 2
NOTE 4
NOTE 3
Figure 3a. Typical Electrical Schematic - ComPac®I A/C, Models AVP20-60
with Mechanical Relays and Contactors

16 ComPac 9/04-12
Figure 3b. Typical Electrical Schematic - ComPac®I A/C, Models AVP20-60
with Electronic Control Board
5
6
TRANSFORMER

17 ComPac 9/04-12
GENERAL NOTES:
1. 208/230 VOLT 60 HZ, 1 PH POWER SUPPLY. SEE DATA PLATE FOR AMPACITY & FUSE SIZE.
DISCONNECT SHOWN.
2. SPEED TAP FOR MULTISPEED MOTORS - SEE MOTOR NAMEPLATE FOR WIRE COLOR.
3. TRANSFORMER IS FACTORY WIRED FOR 230 VOLT OPERATION. FOR LOWER VOLTAGES,
INTERCHANGE ORANGE AND RED LEADS. INSULATE UNUSED LEADS.
4. OPTIONAL FIELD INSTALLED 270 OHM MINIMUM POSITION POTENTIOMETER.
5. CRANKCASE HEATER SHOWN. STANDARD ON RECIPROCATING COMPRESSORS.
NOTE 1
5
TRANSFORMER
NOTE 2
NOTE 3
NOTE 5
NOTE 4
Figure 3c. Typical Electrical Schematic - ComPac®II A/C, Models AVP20-60
with Mechanical Relays and Contactors

18 ComPac 9/04-12
5
TRANSFORMER
Figure 3d. Typical Electrical Schematic - ComPac®II A/C, Models AVP20-60
with Electronic Control Board

19 ComPac 9/04-12
Figure 3e. Typical Electrical Schematic - ComPac®I A/C, Model AVP72
5
TRANSFORMER
GENERAL NOTES:
1. 208/230 VOLT 60 HZ, 1 PH POWER SUPPLY. SEE DATA PLATE FOR AMPACITY & FUSE SIZE.
DISCONNECT SHOWN.
2.SPEED TAP FOR MULTISPEED MOTORS - SEE MOTOR NAMEPLATE FOR WIRE COLOR.
3.TRANSFORMER IS FACTORY WIRED FOR 230VOLT OPERATION. FOR LOWER VOLTAGES,
INTERCHANGE ORANGE AND RED LEADS.INSULATE UNUSED LEADS.
4.SCROLL COMPRESSOR GENERALLY DOES NOT REQUIRE CCH.

20 ComPac 9/04-12
Figure 3f. Typical Electrical Schematic - ComPac®II A/C, Model AVP72
5
TRANSFORMER
GENERAL NOTES:
1. 208/230 VOLT 60 HZ, 1 PH POWER SUPPLY. SEE DATA PLATE FOR AMPACITY & FUSE SIZE.
DISCONNECT SHOWN.
2.SPEED TAP FOR MULTISPEED MOTORS - SEE MOTOR NAMEPLATE FOR WIRE COLOR.
3.TRANSFORMER IS FACTORY WIRED FOR 230VOLT OPERATION. FOR LOWER VOLTAGES,
INTERCHANGE ORANGE AND RED LEADS.INSULATE UNUSED LEADS.
4.OPTIONAL FIELD INSTALLED 270 OHM MINIMUM POSITION POTENTIOMETER.
5.CRANKCASE HEATERS GENERALLY NOT REQUIRED ON SCROLL COMPRESSORS.