Product Manual

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True Food Service Equipment, Inc.
26
26
INSTALLATION / OPERATION INSTRUCTIONS
IF THE COMPRESSOR WILL NOT
RUN
1.Ifthereisnovoltageatthecompressor
terminals,followthewiringdiagram
andcheckbackfromcompressortothe
powersupplytofindwherethecircuitis
interrupted.
2.Ifpowerisavailableatthecompressor
terminals,andthecompressordoesnot
run,checkthevoltageatthecompressor
terminalswhileattemptingtostartthe
compressor.
Ifvoltageatthecompressorterminalsis
below90%ofthenameplatevoltage,it
ispossiblethemotormaynotdevelop
sufficienttorquetostart.Checkto
determineifwiresizesareadequate,
electricalconnectionsareloose,the
circuitisoverloaded,orifthepower
supplyisinadequate.
3.Onsinglephasecompressors,
adefectivecapacitororrelaymay
preventthecompressorstarting.Ifthe
compressorattemptstostartbutis
unabletodoso,orifthereisahumming
sound,checktherelaytoseeiftherelay
contactsaredamagedorfused.Therelay
pointsshouldbeclosedduringtheinitial
startingcycle,butshouldopenasthe
compressorcomesuptospeed.
Removethewiresfromthestarting
relayandcapacitors.Useahighvoltage
ohmmetertocheckforcontinuity
throughouttherelaycoil.Replace
therelayifthereisnotcontinuity.
Useanohmmetertocheckacrossthe
relaycontacts.Potentialrelaycontacts
arenormallyclosedwhentherelayis
notenergized,currentrelaycontacts
arenormallyopen.Ifeithergivesan
incorrectreading,replacetherelay.
Anycapacitorfoundtobebulging,
leaking,ordamagedshouldbereplaced.
Makesurecapacitorsaredischarged
beforechecking.Checkforcontinuity
betweeneachcapacitorterminalandthe
case.Continuityindicatesashort,and
thecapacitorshouldbereplaced.
Substitutea“knowntobegood”start
capacitorifavailable.Ifcompressorthen
startsandrunsproperly,replacethe
originalstartcapacitor.
Ifacapacitortesterisnotavailable,an
ohmmetermaybeusedtocheckrun
andstartcapacitorsforshortsoropen
circuits.Useanohmmetersettoits
highestresistancescale,andconnect
prodstocapacitorterminals.
 a)Withagoodcapacitor,the
indicatorshouldfirstmovezero,and
thengraduallyincreasetoinfinity.
 b)Ifthereisnomovementof
theohmmeterindicator,anopencircuit
isindicated.
 c)Iftheohmmeterindicator
movestozero,andremainsthereorona
lowresistancereading,ashortcircuitis
indicated.Defectivecapacitorsshouldbe
replaced.
4.Ifthecorrectvoltageisavailable
atthecompressorterminals,andno
currentisdrawn,removeallwiresfrom
theterminalsandcheckforcontinuity
throughthemotorwindings.Onsingle
phasemotorcompressors,checkfor
continuityfromterminalsCtoR,and
CtoS.Oncompressorswithlinebreak
inherentprotectors,anopenoverload
protectorcancausealackofcontinuity.
Ifthecompressoriswarm,waitonehour
forthecompressortocoolandrecheck.
Ifcontinuitycannotbeestablished
throughallmotorwindings,the
compressorshouldbereplaced.
Checkthemotorforgroundbymeansof
acontinuitycheckbetweenthecommon
terminalandthecompressorshell.If
thereisaground,replacethecompressor.
5.Ifthecompressorhasanexternal
protector,checkforcontinuitythrough
theprotectororprotectors.Allexternal
inherentprotectorsoncompressorscan
bereplacedinthefield.
IF THE MOTOR COMPRESSOR
STARTS BUT TRIPS
REPEATEDLY ON THE
OVERLOAD PROTECTOR
1.Checkthecompressorsuctionand
dischargepressureswhilethecompressor
isoperating.Besurethepressuresare
withinthelimitationsofthecompressor.
Ifpressuresareexcessiveitmaybe
necessarytocleanthecondenser,purge
airfromthesystem,replacecrankcase
pressureregulatingvalve.
Anexcessivelylowsuctionpressuremay
indicatealossofcharge.
Onunitswithnoservicegaugeparts
wherepressurescanbechecked,check
condensertobesureitiscleanandfan
isrunning.Excessivetemperatureson
suctionanddischargelinemayalso
indicateabnormaloperatingconditions.
2.Checkthelinevoltageatthemotor
terminalswhilethecompressoris
operating.Thevoltageshouldbewithin
10%ofthenameplatevoltagerating.If
outsidethoselimits,thevoltagesupply
mustbebroughtwithintheproper
range,oramotorcompressorwith
differentelectricalcharacteristicsmustbe
used.
3.Checktheamperagedrawnwhilethe
compressorisoperating.Undernormal
operatingconditions,theamperage
drawnwillseldomexceed110%ofthe
nameplateamperage.Highamperage
canbecausedbylowdamage,defective
runningcapacitors,oradefectivestarting
relay.