Lennox MHA Series - Servicing Indoor Unit Refrigeration Circuit; Collecting Refrigerant Into Outdoor Unit; Air Purging With Vacuum Pump; Evacuation after Servicing the Outdoor Unit Refrigeration Circuit

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• Besuretocheckforgasleaks.
12.6. Servicing Indoor Unit Refrigeration
Circuit
12.6.1. Collecting Refrigerant into Outdoor Unit
• Conrmthatboththetwo-wayandthree-wayvalves
aresettotheopenedposition
• Removethevalvestemcapsandconrmthatthevalve
stemsareintheopenedposition.
• Besuretouseahexagonalwrenchtooperatethe
valvestems.
• Connectthechargehosewiththepushpinofhandlelo
tothethree-wayvalvesgasserviceport.
• Airpurgingofthechargehose-OpenthehandleLo
valveofthemanifoldvalveslightlytopurgeairfromthe
chargehoseforvesecondsandthencloseitquickly.
• Setthetwo-wayvalvetothecloseposition.
• Operatetheairconditioneratthecoolingcycleand
stopitwhenthegaugeindicates0.1MPa(14psi).
• Setthethree-wayvalvetotheclosedposition
immediately
• Dothisquicklysothatthegaugeendsupindicating0.3
to0.5Mpa(43-72psi).
• Disconnectthechargeset,andtightenthetwo-way
andthree-wayvalve’sstemnuts.
• Useatorquewrenchtotightenthethree-wayvalves
serviceportcaptoatorqueof18N.m.
• Besuretocheckforgasleakage.
12.6.2. Air Purging with Vacuum Pump
• Completelytightenthearenutsoftheindoorand
outdoorunits,conrmthatboththetwo-wayandthree-
wayvalvesaresettotheclosedposition.
• Connectthechargehosewiththepushpinofhandlelo
tothethree-wayvalvesgasserviceport.
• Connectthechargehoseofhandlehiconnectiontothe
vacuumpump.
• FullyopenthehandleLoofthemanifoldvalve.
• Operatethevacuumpumptoevacuate.
• Makeevacuationfor30minutesandcheckwhetherthe
compoundmeterindicates-0.1Mpa(500microns).If
themeterdoesnotindicate-0.1Mpa(500microbars)
afterpumping30minutes,itshouldbepumped20
minutesmore.Ifthepressurecan’tachieve-0.1Mpa
(500microbars)afterpumping50minutes,please
checkiftherearesomeleakagepoints.
• FullyclosethehandleLovalveofthemanifoldvalve
andstoptheoperationofthevacuumpump.Conrm
thatthegaugeneedledoesnotmove(approximately
veminutesafterturningoffthevacuumpump).
• Turnthearenutofthethree-wayvalvesabout45°
counterclockwiseforsixorsevensecondsafterthegas
comingout,thentightenthearenutagain.Makesure
thepressuredisplayinthepressureindicatorisalittle
higherthantheatmospherepressure.Thenremovethe
chargehosefromthethree-wayvalve.
• Fullyopenthetwo-wayvalveandthree-wayvalveand
securelytightenthecapofthethree-way
12.7. Evacuation after Servicing the Outdoor
Unit Refrigeration Circuit
12.7.1. Evacuation of the Complete Refrigeration
Circuit, Indoor and Outdoor Unit
• Conrmthatboththetwo-wayandthree-wayvalves
aresettotheopenedposition.
• Connectthevacuumpumptothree-wayvalve’sservice
port.
• Evacuationforapproximatelyonehour.Conrmthat
thecompoundmeterindicates-0.1Mpa(500Microns/
29.9in.hg).
• Closethevalve(Lowside)onthechargeset,turnoff
thevacuumpump,andconrmthatthegaugeneedle
doesnotmove(approximately5minutesafterturning
offthevacuumpump).
• Disconnectthechargehosefromthevacuumpump.
12.7.2. Refrigerant Charging
• Connectthechargehosetothechargingcylinder,open
thetwo-wayvalveandthethree-wayvalve.
• Connectthechargehosewhichyoudisconnectedfrom
thevacuumpumptothevalveatthebottomofthe
cylinder.IftherefrigerantisR-410A,makethecylinder
bottomuptoensureliquidcharge.
• Purgetheairfromthechargehose
• Openthevalveatthebottomofthecylinderandpress
thecheckvalveonthechargesettopurgetheair(be
carefuloftheliquidrefrigerant).
• Putthechargingcylinderontotheelectronicscaleand
recordtheweight.
• Openthevalves(Lowside)onthechargesetand
chargethesystemwithliquidrefrigerant.Ifthe
systemcannotbechargewiththespeciedamount
ofrefrigerant,orcanbechargedwithalittleatatime
(approximately150geachtime),operatingtheair
conditionerinthecoolingcycle;however,onetimeis
notsufcient,waitapproximately1minuteandthen
repeattheprocedure.
• Whentheelectronicscaledisplaystheproperweight,
disconnectthechargehosefromthe3-wayvalve’s
serviceportimmediately
• Ifthesystemhasbeenchargedwithliquidrefrigerant