Delorean DMC-12 1981 Technical document

TECHNICAL
INFORMATION
MANUAL
P.J.GRADYINC(516)589-6224(800)350-7429FAX [phone]

P.J.GRADYINC(516)589-6224(800)350-7429FAX[phone]

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DELOREANMOTORCOMPANY
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TECHNICALINFORMATIONMANUAL
1981DeLorean
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TechnicianName.
Dealership Name.
InstructorName_
Date
PRINTED3-81

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FOREWORD
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This servicepublicationhasbeenpreparedbytheServiceTrainingDepartmentof
DeLoreanMotorCompanytoassistinunderstandingthedesignconceptsandthe
generaloperationoftheDeLorean.Itisintendedprimarilyfortheexperiencedand
qualifiedautomotivetechnicianswhohavebeenselectedtoservicetheDeLorean.
Thispublicationincludesthegeneraldescriptionandoperationofvehiclesystems
usedonthisvehiclewhichtheselectedtechniciansarebasicallyfamiliarwithaswell
asthemorespecificallydetaileddescriptionsandoperationforthesystemswhich
maybeuniquetothisvehicleand/ortheservicetechnician.
Allinformation,specificationsandillustrationsinthispublicationarebasedonthe
latestproductinformationavailableatthetimeofprinting.DeLoreanMotorCompany
reservestherighttomakechangesorrevisionsatanytimewithoutnotice.However,it
istheobjectiveofDMCandtheServiceTrainingDepartmenttoprovidetheDMCserv-
icetechnicianwithasmuchaccurateandusableserviceinformationasisavailable,
asquicklyaspossible,inordertosustaina highqualityservicestandard.
IMPORTANT:
TheDeLoreancontainsmanypartsdimensionedinthemetricsystem.Duringany
serviceprocedure,replacementfastenersmust have thesamemeasurementsand
strengtnasthosefastenersremoved,eithermetricorcustomary.Thenumbersonthe
headsofmetricboltsandonthesurfacesofmetricnutsindicatetheirstrength.Cus-
tomaryboltsuseradiallinesontheirheadsforstrengthindicatorswhilemostcustom-
arynutsdonothavestrengthindicators.Mismatchedorincorrectfastenerscanresult
invehicledamageormalfunction,orpossiblypersonalinjury.Fastenersremoved
fromthevehicleshouldbereusedinthesamelocationswheneverpossibleexcept
whenindicatedotherwise.Whenfastenersarenotsatisfactoryforreuse,careshould
betakentoselecta replacementfastenerthatisequivalenttotheoriginalquality.
Copyright© 1981DeLoreanMotorCompany
AllRightsReserved

TABLEOFCONTENTS
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I. GENERALINFORMATION1
A.Engine3
B.Transmission- Manual5
C.Clutch7
D.Transmission- Automatic8
E.FrontSuspension9
F.RearSuspension 10
G. Steering 11
H.Brakes 12
I. HeatingandAirConditioningSystem13
J. BodyandChassis17
II. ENGINEELECTRICAL19
A.ElectronicIgnitionSystem21
B.StarterMotorCircuit29
C.ChargingSystem32
D.CoolingFanCircuit35
III. FUELINJECTION39
IV.EMISSIONCONTROLS63
A.LambdaControlSystem65
B. Idle SpeedControlSystem77
C.EvaporativeEmissionControlSystem84
D.Air Inlet System87
E.IgnitionVacuumAdvanceControl88
F.DecelerationControl89
V.CHASSISELECTRICAL91
A.FusesandFuseBox93
B.RelayCompartment94
C.IgnitionSwitchCircuits96
D.WindshieldWiperSystem99
E.ExteriorLightingCircuit103
F.DoorOperated InteriorLampCircuits .111

TABLEOFCONTENTS
(con't)
VI. ENGINEADJUSTMENTS,TESTSANDDIAGNOSIS
A.Adjustments
1. IgnitionTiming 117
2. Idle Speed118
3.COEmission119
B.SystemOperationTests
1. LambdaSystem122
2. Idle SpeedControlSystem 124
C.DiagnosticCharts
1. IgnitionSystem- "EngineWillNotStart"126
2. FuelSystem- "EngineWillNotStart"128
3.LambdaSystem130
4. TroubleshootingDiagnosticChart132
VII. SPECIFICATIONS& CAPACITIES133
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GENERALINFORMATION

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ENGINE
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GENERALDESCRIPTION
TheDeLoreanispoweredbya liquidcooled,2.8liter,rearmounted,aluminumalloy
90°V-6uneven-fireenginewithtwo(2)chaindrivenoverheadcamshafts.
Theflywheel(orflexplate)endoftheengineisreferredtoasthefrontoftheengine
duetotheuniquerearenginedesign.Therefore,thetimingcoveranddrivebelt pul-
leysarelocatedattherearoftheengine.Therightand leftside oftheengineisdeter-
minedasviewedstandingattherearofthevehiclelookingintotheenginecompart-
ment.
Enginefiringorderis1,6,3,5,2,4.
The #1 cylinderislocatedattherightfrontoftheenginefollowedwith#2and#3 cyl-
inders.Cylinder#4islocatedattheleftfrontoftheenginefollowedwith#5and#6
cylinders.
CYLINDERCRANKCASEASSEMBLY:Thecylindercrankcaseassemblyconsistsof
aluminumalloyupperandlowercrankcases.Theuppercrankcasecontainssix(6)
castironcylinderlinersandhousesthecrankshaftwhichissupported byfour(4) cast
ironmainbearingcaps.Theuppercrankcasealsocontainsthechaindrivenoilpump
driveanddrivengears.Theoilpumpbodyisa machinedportionoftheuppercrank-
case. Thelowercrankcaseprovidessideenginemountlocationsandcompletesthe
crankcaseassembly.Thealuminumoilpan,whichhouses theoil splashshieldandoil
pickupassembly,issecuredtothelowercrankcase.
CYLINDERHEADS: The aluminum alloy cross-flow cylinder heads,havehemispheri-
calchambersandindividualintakeandexhaustportsforeachcylinder.Boththein-
takeandexhaustvalveguides(8MM)arepressedintothecylinderhead.
NOTE: CYLINDERHEADRESURFACINGISNOTPERMITTED.
Thesteelvalveseatsarefittedtothecylinderhead.
VALVETRAIN:Eachcylinderheadhasa chaindrivenoverheadcamshaft.The cam-
shaftoperatesbothintakeandexhaustvalvesoneachbankbymeansofadjustable
rockerarmsmountedona single,commonrockershaft.Therockerarmsare posi-
tionedandheldinplacebymeansoftwo(2)spacersandone(1)thrustspringper
cylinder.
Thehollowrockerarmshaft,whichalsodistributesengineoilthroughcalibrated
holestothevalvetrainandcamshaft,ismountedandsecuredtoeachcylinderhead
withfour(4)rockershaftsupports.

CAMSHAFTANDDRIVE:Eachchaindrivencastironcamshaftissupportedatfour
(4)contactareas.Steelcrankshaftsprocketsdrivethetimingchains(2)whichinturn *1
drivethecamshaftsprockets(2).J
PISTONSANDCONNECTINGRODS:Eachaluminumalloypistonusestwo(2)com- _
pressionringsandone(1)oil ring. Thesteelpistonpinhasa floatingfitinthepiston.
Thepinsareretainedintheconnectingrodbya hot'pressfit.Theconnectingrod
bearingsarelubricatedviadrilledoilpassageslocatedinthecrankshaftjournals.
CRANKSHAFT:Thecastironcrankshaftissupportedwithfour(4)mainbearingsand
mainbearingcaps.Thisunevenfireenginecrankshafthasthree(3)connectingrod
journals.Lubricationfortheconnectingrodjournalisdeliveredviadrilledoilpas-
sagesinthecrankshaft,crankshaftmainbearingsandmainbearingjournals.The
crankshaftissealedateachendwitha lip seal.
Therearethree(3)steeldrivesprocketsmountedonthe rearof thecrankshaft.These
three(3)chainsprocketsdrive:
-rightcamshaftsprocket
-leftcamshaftsprocket
-oilpumpsprocket
Thedrivechainsandsprocketsarecoveredbyatimingchaincoverwhichissecured
totheupperandlowercrankcaseassembly.
ENGINECOOLING:Thevehicle has two(2)electric fans forradiatorcoolingmounted
atthefrontofthevehicle.Thesefansareactivatedwhentheenginecoolanttempera-
tureexceeds 97°C (206° F)anddeactivatedat 91°C (195°F) Operationofthesefans
iscontrolledbyatemperatureswitchlocatedonthecoolantreturnpipeintheengine
compartment.
Thewaterpump,locatedattherearoftheengine,isbeltdrivenbythecrankshaft pul-
ley.Thethermostatishousedinthetopofthewaterpumpunderthethermostathous-
ingcover.Thethermostathousingcoverisequippedwithanairbleedscrewusedto
purgetheairfromthecoolantsystemwhenrefilling.
Coolantleavingtheengineisdirectedthrougha seriesofpipesandhosecouplings
alongthe leftside of the vehicle center tunneltotheradiator.Coolantleavingthe radi-
atorisdirectedthrougha seriesofpipesandhosecouplingsalongtherightsideof
thevehiclecentertunneltotheengine.
Thecoolantexpansiontank(fillpoint)locatedontherightsideoftheenginecom-
partment,isconnectedtothecoolantreturnpipebya hose.
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TRANSMISSION- MANUAL
GENERALDESCRIPTION
Themanualtransmission is a constantmeshfivespeed.Allforwardgearsarefully
synchronizedforeaseofshifting.Thealuminumcaseconsistsoftwohalveswhich,
whenrepairisnecessary,canbeseparatedtoprovideeasyaccesstointernalparts.
Thefinaldrivecomponentsarealsocontainedwithinthetransmissioncase.Boththe
finaldriveandtransmission usethe same lubricanteliminating theneed fora separate
finaldrivelube.
Thepowertrainconsistsof:
A.Primary(input)shaft
B.Secondary(output)shaft
C.Sixdrivinggears
D.Sixdrivengears
E.Onereverseslidergear
Theselectorcontrolconsistsof:
A.Fourshiftrodsandshiftforks
B.Onepivotinginterlock
C.One selector leverandshaft
D.Oneselectorshaftarm

OPERATION
Allforwardgearpowerflowistransferredvia: \
A.Primaryshaft(input)
B.Theselecteddrivinggear(primaryshaft)
C.Theselecteddrivengear(secondaryshaft) **|
D.Pinionshaft/finaldriveuniti
Reversegearpowerflowistransferredbymeansof:
A.Primaryshaft *"|
B.Reversedrivinggear _'
C.Reverseslidergear
D.Reversedrivengear ^
E.Pinionshaft/finaldriveunitj
Allgearsareselectedmanuallybythedriverusingthegearshiftleverattachedtothe
selectorlevermountedonthesideofthetransmissionrearhousing.Insidetherear
<SI)
housing, a selectorshaftarm,attachedtotheselectorshaft,fitsthrougha slotinthe _!
pivotinginterlock.Whena gearisselected,theselectorshaftarmmovestheinterlock
to thedesiredpositionandmovestheappropriateshiftrodin or outdependingonthe
gearselected.Theshiftforkattachedtotheshiftrodmovesthedesiredgearintothe
properpositionwhilethesychronizerringmatchesthespeedofthetwogearsbeing
coupled. Thisshiftsequenceisrepeatedforallforwardgears.Reverseoperationis
the samewiththeexceptionofthesynchronizer ring, whichisnotrequired, since the
vehicleshouldbestationarywhenshiftingtoreverse.
Gearratiosareasfollows:
1stGear:
2ndGear:
3rdGear:
4thGear:
5thGear:
ReverseGear:
3.36
2.06
1.38
1.06
0.82
3.18
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CLUTCH
GENERALDESCRIPTION
Thevehicle,whenequippedwiththefivespeedmanualtransmission,usesa single
drydisctypeclutch.Theclutchishydraulicallyoperated.Thepressureplateisadia-
phram springtypeandthedischasa springcushionedhub.A self-aligning,sealed
ball-typethrow-outbearingisusedtodepressthediaphramspring.Theclutchhasits
ownfluidreservoirandmastercylinderwhichprovideshydraulicpressurewhenthe
clutchpedalisdepressed.
OPERATION
Theclutchpedalisconnectedtothemastercylinderwitha pushrod.Whenthepedal
isdepressed,thepushrodexertspressureagainstthemastercylinderpiston.Asthe
pistonbeginstomove,itdrawsfluidfromthefluidreservoirandforcesitthroughthe
hydrauliclinetotheslavecylinderpiston.Slavecylinderpistonpressurecausesthe
clutchforktomovethethrow-outbearingagainstthepressureplate. As thediaphram
springisdepressed,pressureonthediscisreleasedandtheclutchdisengages.When
theclutchpedalisreleased,theprocedureisreversedandtheclutchengages.
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TRANSMISSION- AUTOMATIC
GENERALDESCRIPTION
Thethree(3)speedautomatictransmissionusesa conventionaltorqueconverter.
Thisconverterhas a singlestatorsupportedon a one-wayrollerclutch.Thefinaldrive
unitiscontainedwithinthetransmissioncase.Gearreduction,directdrive,and
reverseareachievedusingone (1) planetarygearset,two(2)reactionmembers,and
two(2)internalclutchpacks.Hydraulicpressureforthistransmissionisdeveloped
withacrescent geartype oilpump. The pumpisdrivenby a shaftwhich runs theentire
lengthofthetransmissioncase.Thisshaftissplinedtotheconverterandturnsat
enginespeed.Mainlinepressureisregulatedbya pressureregulatorvalveanda
vacuumoperatedactuator.Asenginevacuum decreases, thevalveincreasesmain
linepressuretoassurepositiveapplicationoftheclutchesandreactionmembers.
Theshiftvalves in thevalvebodyarecontrolledbya computergovernorassembly
andtwo(2)electricsolenoids.Bycomparison,a conventionalvalvebodyusesa
mechanicalgovernorand a vacuummodulator(orthrottlevalve)toperform this same
function. Thevalvebodyisnotservicableandmustbereplacedasa unitifrequired.
Thehydraulictransmissionisoperatedandlubricatedbyautomatictransmission
fluidwhilethefinaldriveassemblyisina separateareafilledwithgearlube.
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FRONTSUSPENSION
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GENERALDESCRIPTION
Thefrontsuspensionisa fullyindependenttypewithupperandlowercontrolarms,
stabilizerbarandsteeringknuckleassembly.Telescopicshockabsorbers,securedto
thechassisframetowerattheabsorber'supperendandtothelowercontrolarmat
theabsorber'slowerend,arepositionedthroughthecoilsprings.
Thesinglefronthubbearingsupportsthehubassemblyonthespindlewhichis
fastenedtothesteeringknuckle.Thesteeringknuckleissecuredtotheupperand
lowercontrolarmswithupperandlowerballjointsandtothesteeringsystemwithan
adjustableball-typetierod.
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REARSUSPENSION
GENERALDESCRIPTION
Therearsuspensionisafully independenttypewitharadius arm(trailing), upper and
lowerlinksanda rearhubcarrier.Telescopicshockabsorbers,securedtothechassis
frameattheabsorber'supperendandtotherearhubcarrierattheabsorber'slower
end, arepositionedthroughthecoilsprings.
Therearhubcarrierisattachedtothechassisframewithupperandlowerlinksaswell
astheradiusarm.
Rearsuspensiontoe-inisachievedbyshimmingtheradiusarmatits frame attaching
location.
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STEERING
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GENERALDESCRIPTION
Thesteeringsystemconsistsofa collapsiblesteeringcolumnassembly,aninter-
mediateshaftassemblyanda rackandpiniontypesteeringunit.
Thesteeringcolumnassemblyissupportedinthepassengercompartmentwithan
adjustable(upanddown)bracket.Eachendofthesteeringcolumnshaftissplined.
Theuppersplinedendisdesignedtoacceptthesteeringwheel.Thelowersplined
endofthesteeringcolumnshaftfitsthroughanopeninginthedriver'sfootwelland
issealedwitha gasketandplate.
Thelowerendofthesteeringcolumnshaftissecuredtotheupperuniversaljointof
theintermediateshaft.Theloweruniversaljointoftheintermediateshaftissecured
tothesplinedstubshaftofthesteeringgear.
Thesteeringunitconsistsofa rackandpinionassembly,tierodassembliesandtie
rodends.Eachendoftherackandpinionassemblyisprotectedfromtheelements
witha flexiblerubberbootwhichissecuredwithtwo(2)clamps.Theadjustabletie
rodends,forobtainingpropertoe-inspecifications,arefastenedtothesteering
knuckles.
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BRAKES
GENERALDESCRIPTION
Thevehicleisequippedwitha fourwheel,vacuumassisted,hydraulicdiscbrake
system. Thediscbrakesareappliedwithseparatefrontandrearhydrauliccircuits.
Thehydraulicpressureforthesecircuitsoriginatesata tandemmastercylinder
whichisoperatedwithpushrods.Brakeapplicationisassistedwiththeaidofa
mechanical/vacuumpowerservounitwhichisactivatedbybrakepedalapplication.
Theparkbrakemechanicallyoperatestherearbrakesonly.
Eachwheelassemblyisequippedwitha fixedcalipercontainingtwoopposingpis-
tons(attachedtoknuckleorcarrier),a brakedisc(positionedoverthehubandwheel
studs)anda setorbrakepads.
Inadditiontotheservicebrakecalipersandpads,therearbrakesareequippedwith
independentandseparateparkbrakecaliperandpadassemblies.Theparkbrake
calipersandpadsareoperatedwiththeparkbrakeleverinsidethedriver's
compartmentbymeansoftwo(2)separatecablestoprovideparkandemergency
braking ofthereardiscs.Theparkbrakecaliperandpadassembliesaresecuredto
therearservicebrakecalipers.Theparkbrakecaliperandpadassembliesareself-
adjustingbymeansofa springloadedrachetingpawlincorporatedwithinthecaliper
applylever.
Thetandemmastercylinderconsistsoftwo(2)independentcylindersina single
casting. Shouldonecylinderorsystem fail, theothersystemwillremainoperational.
Eachhydraulicsystem(frontandrear)hasa separatebrakefluidsupplywellinthe
brakefluidreservoirwhichismountedtothetopofthemastercylinder.Thebrake
fluidreservoirisequippedwitha floatactuated,lowfluidwarningindicator.
However,thissystemisnotequippedwitha lowpressureindicator,a meteringvalve,
proportioningvalveora combinationofthesevalves.
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Thepowerassistfromthebrakeservounitisdevelopedbyenginevacuum.Engine
vacuum, obtainedfromanintakemanifoldfitting,isappliedtobothsidesofa
diaphragminsidetheservounit.Depressingthebrakepedalwillallowatmospheric
pressuretoenteronesideofthediaphragm.Thisdifferenceinpressuredevelopsthe
powerassistusedinapplyingthebrakesystems.Theservounitislocatedbetween
thebrakepedalandmastercylinder.Theapplypressureistransferredthroughtwo
(2)in-linepushrods.Should a vacuumfailureoccur,thetwo(2)push rods will actas a
singlerodandthebrakeswillcontinuetooperateintheunassisted,conventional
manner;however,additionalbrakepedaleffortwillberequired.A vacuumcheck
valveisusedinthesupplylinewhereitconnectstotheservounit.Thischeckvalve
preventsvacuumlossfromtheservounit after theenginestopsrunningandprovides
enoughvacuumreserveforemergencybrakeapplication.
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HEATINGANDAIRCONDITIONINGSYSTEM
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GENERALDESCRIPTION
Thevehicleuses a dual-functionairconditioningsystemwhichprovidesbothheating
andcooling.TheairconditioningsystemistheCyclingClutchOrificeTubetype
(C.C.O.T.).Thissystemusesa pressuresensingswitchtopreventevaporatorfreeze-
upbycyclingthecompressoronandoff.Heatingiscontrolledbytheamountofair
flowthroughtheheatercore.Thisflowiscontrolledbya temperaturedooroperated
witha cableconnectedtothetemperatureknob.
OPERATION
CONTROLFUNCTIONS:Airisdrawnintothesystembya faneitherthroughthe
freshairintake(locatedjustaheadofthewindshield),orfromtheinterioroftheve-
hicledependingonthepositionofthere-circulationdoor.Thefanthenforcestheair
throughtheevaporatorcoretothetemperaturedoor.Thepositionofthetemperature
doorcontrolstheamountofsystemairdirectedthroughtheheatercore.Twomode
doors(mountedona commonshaft)directtheconditionedairtoeitherthefootwell/
windshieldchamberorthedoor/facelevelventchamber,or both. The footwell/wind-
shieldchambercontainsa horizontallymounteddoorwhichdirectstheconditioned
aireithertothewindshieldorthefootwell.Thedoor/facelevelventalsocontainsa
horizontallymounteddoorwhicheithershutsofffacelevelventsorshutsoff a bridg-
ingductconnectingwiththewindshieldvent.
Alldoors,withtheexceptionofthecableoperatedtemperaturedoor,arevacuum
operatedbydiaphragmactuators.Theairconditioning/heaterselectorswitchhas
twofunctions.Onefunctionistosupplyvacuumtothecorrectdooractuators.The
other function istosupplyelectriccurrenttotheairconditioningcompressorandthe
blowerfanasnecessarywhenthedifferentpositionsareselected.
Thecontrolofvacuumdistributionisachievedbymeansofa five(5)portrotaryvalve.
Therotationofthisvalveiscontrolledbyair conditioning/heater selectormovement.
Avacuumhoseharnessconnectsalldoorvacuumactuatorstotheairconditioning/
heaterselector.Thevacuumhoseharnessalso delivers theoperatingvacuumsource
tothe five-port rotaryvalve.Vacuumforthissystem'soperationissuppliedbyengine
vacuumandstoredina vacuumreservoirtank(locatedintheleftrearbodysection).
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Reservoirtankvacuumismaintainedaftertheengineisshutoffbymeans of vacuum
supplylinecheckvalve.Asthefive(5)portrotaryvalveisturned(byselectormove-
ment),variousvacuumportswillaligntoeitherventorsupplyvacuumtotheproper
actuatorsrequiredforthedesiredoperatingmode.
Theconnectionandswitchingsequenceoftheselectorswitchisasfollows:
^59
VACUUMCONNECTIONS
Port2 - Black/Brown
LowerModeDoor
Port1 - Black
Supplyfrom
Reservoir
SELECTORROTARYVALVE
Port3 - Black/Orange
RecirculationDoorand
WaterValve
Port4 - Black/Blue
WindshieldVentDoor
Port5 - Black/Red
UpperModeDoorandFaceLevel
VentDoor
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VACUUMSWITCHING
SELECTORCONTROLPOSITION
CONNECTION
1Source
2Lowermodedoor
3Re-circulationdoor
&watervalve
4Windshielddoor
5Uppermodedoor&
facelevelvent
OFF
Seal
Vent
Vent
Vent
MAX
Vac
Vac
Vac
Vent
NORM
Vac
Vac
Vent
Vent
BI-LEVELVENT
Vac
Vent
Vent
Vent
Vac
Vac
Vent
Vent
HEATER
Seal
Vent
Vent
Vent
DEFROST
Vac
Vent
Vent
Vac
VentVacVacVacVacVentVent
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