MG MG6 Series 2011 - Operation

HVACSystem
HVAC-ATC
Operation
ATCSystemControl
ATCsystemisaclosedloopcontrolsystemwhichaimsto
achieveacomfortableclimateinthepassengercompartment.
Inordertoachievethis,thesystemmaintainsthefollowingtwo
conditions:
•Thetemperaturedistributionrangingfromoorlevelto
rooflevel
•Theaveragetemperatureinthepassengercompartment
Thesystemaimstoachieveatemperaturedistributionwitha
warmeroorareasandacoolerroofareausingthefollowing
inputs:
•Setpassengercompartmenttemperatureasselectedby
theuser
•Incartemperature
•Ambientairtemperature
•Evaporatortemperature
•Heatercoretemperature
Thesesinputsareinterpretedbythe
ATCECUresultinginthe
followingoutputs:
•Motorpositionfortheblendap
•Motorpositionfortheairdistributionap
•Blowerspeed
Thesensorsandcontrolpanelswitchesinputtothe
ATC
ECU,andATCECUthenoutputstotheheaterassembly
andcommunicateswiththeBCM.TheBCMisconnectedto
theECMviatheHSCANBus,andrelaysmessagesbetween
theATCECUandtheECM.
Whenthesystemisrstswitchedon,theA TCECUresumes
thecontroloutputsinusewhenthesystemwaslastswitched
off.Ifconditionshavechanged,oradifferentmodeisselected
toswitchthesystemon,thecontroloutputsareimmediately
changedtoproducetherequirednewsettings.
Thesystemoperatesinautomatic,economyanddefrost
modes,withmanualoverridesoftheinletairsource,blower
speedandairdistribution.Theairtemperatureisautomatically
controlledinalloperatingmodes.
Intheautomaticmode,the
ATCECUoperatesthesystem
towarm-uporcooldownthepassengercompartmentto
establishandmaintainthetemperatureselectionsonthe
controlpanel,whiledirectingtheairtothoseoutletsmost
comfortablefortheoccupant(s).Ifadifferencebetweenthe
LHandRHtemperatureselectionscausesaconictofthe
requiredblowerspeedorairdistributionsettings,priorityis
giventoachievingthetemperaturerequestedonthedriver's
sideofthecontrolpanel.
whilethesystemisintheautomaticordefrostmode,and
therefrigerantcompressorismanuallyselectedoff,A TCECU
enterstheeconomymodetoreducetheloadontheengine.
Economymodeoperationissimilartotheautomaticmode,
butwithouttheabilitytocoolthepassengercompartment
iftheambienttemperatureishigherthanthetemperature
selectionsmadeonthecontrolpanel,ortodehumidifythe
freshorrecirculatedair.
Inthedefrostmode,theA TCECUsetstheinletairsourceto
freshair,theblowertomaximumspeed,theairdistributionto
windscreenandsidewindows,andoutputssignalstotheBCM
tooperatetherearwindowheater.A TCECUswitchesonthe
rearwindowheatertimerforapredeterminedduration.If
HRWisonATCECUresetsthetimer.Ifthedefrostmodeis
selectedoffwhiletherearwindowheaterisstillon,theheater
remainsonuntiltheendofthecycleunlesscancelledusingthe
rearwindowheaterswitch.
Whentherecirculationbuttonispressed,therecirculation
apdecidesthesourceoftheincomingair,eitherfreshair
fromoutsidethevehicleorreuseofairalreadypresentinthe
passengercompartment.Therecirculationapiscontrolled
bythe
ATCECUintwopositions:
•Freshair
•Recirculation
PressingtherecirculationbuttonwhileAUTOisnoton,
switchestherecirculationapfromfreshairtorecirculation
andviceversa.Whentherecirculationbuttonispressed
duringfreshairmode,theactuatorswitchestheapto
recirculationmode,and,iftheA/Cisnotswitchedona
4minutetimedelaywillbegin.Whenthetimerexpiresit
returnstofreshairmode.
Alongpressoftherecirculationbutton(2secondsor
more)setstheaptorecirculationmodepermanently.The
recirculationiconinthe
LCDashesasanindicationofthis.A
secondarypressoftherecirculationbuttoncancelsthismode.
Parkedrecirculationautomaticallysetstheinletairsource
torecirculationwhentheignitionisswitchedoff,without
illuminatingtheiconintheLCDtopreventdampairfrom
enteringthepassengercompartment.Whenthehandsetis
docked,theA TCECUsetstheinletairsourcetofreshair,
afteratimedelayofapproximately5seconds.Thedelay
allowstimefortheenginetobestarted,whichwillmaskany
operatingsoundfromtheservomotor.
CompressorControl
WhentheengineisrunningandtheECONbuttonispressed,
theA/CECUextinguishestheECONicon,illuminatesA/C
iconintheLCDdisplayandchangestherequesttocompressor
on.ThissendsasignalviatheBCMtotheECMengagingthe
compressorclutch.Whentheignitionison,theBCMoutputs
Version2.0504