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CentralAirConditioningPlants

Inourdepartment,theseplants(Aircooledorwatercooled)arecommonlyavailableabove10TR

upto100TR.ThesetypesofplantsaremoresuitableforlargeinstallationssuchasAIRRadioStudio/TV

StudioBuildingsandHighPowerTransmitterBuildings. Inwatercooledplants,externalcoolingtowers/

waterspraypondswithwatersofteningplantsare thecommon features.Theseare invariablyprovided

withAHU

(Air

Handling

Unit)

and

supply

&

return

ducts

for

carrying

air.

Thecentralairconditioningplantsorthesystemsareusedwhenlargebuildings,hotels,theaters,airports,

shoppingmallsetcaretobeairconditionedcompletely.Thewindowandsplitairconditionersareusedfor

singleroomsorsmallofficespaces.Ifthewholebuildingistobecooleditisnoteconomicallyviabletoput

windowor splitair conditioner ineachandevery room.Further, these smallunits cannot satisfactorily

coolthelargehalls,auditoriums,receptionsareasetc.

In the central air conditioning systems there is a plant room where large compressor, condenser,

thermostaticexpansionvalveandtheevaporatorarekept inthe largeplantroom.Theyperformallthe

functions

as

usual

similar

to

a

typical

refrigeration

system.

However,

all

these

parts

are

larger

in

size

and

havehighercapacities.Thecompressorisofopenreciprocatingtypewithmultiplecylindersandiscooled

by thewaterjust like theautomobileengine.Thecompressorand thecondenserareof shelland tube

type.Whileinthesmallairconditioningsystemcapillaryisusedastheexpansionvalve,inthecentralair

conditioningsystemsthermostaticexpansionvalveisused.

Thechilledispassedviatheductstoalltherooms,hallsandotherspacesthataretobeairconditioned.

Thusinalltheroomsthereisonlytheductpassingthechilledairandtherearenoindividualcoolingcoils,

andotherpartsoftherefrigerationsystemintherooms.Whatiswegetineachroomisthecompletely

silent andhighlyeffective air conditions system in the room. Further, the amountof chilledair that is

neededintheroomcanbecontrolledbytheopeningsdependingonthetotalheatloadinsidetheroom.

Thecentralairconditioningsystemsarehighlysophisticatedapplicationsoftheairconditioningsystems

andmanyatimestheytendtobecomplicated.Itisduetothisreasonthatthereareveryfewcompanies

intheworldthatspecializeinthesesystems.Inthemoderneraofcomputerizationanumberofadditional

electronicutilitieshavebeenaddedtothecentralconditioningsystems.

Therearetwotypesofcentralairconditioningplantsorsystems:

1)DirectexpansionorDXcentralairconditioningplant:

In

this

system

the

huge

compressor,

and

the

condenser

are

housed

in

the

plant

room,

while

the

expansion

valveandtheevaporatororthecoolingcoilandtheairhandlingunitarehousedinseparateroom.The

coolingcoilisfixedintheairhandlingunit,whichalsohaslargeblowerhousedinit.Theblowersucksthe

hotreturnairfromtheroomviaductsandblowsitoverthecoolingcoil.Thecooledairisthensupplied

throughvariousductsandintothespaceswhicharetobecooled.Thistypeofsystemisusefulforsmall

buildings.

2)Chilledwatercentralairconditioningplant:

http://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50160.aspxhttp://www.brighthub.com/engineering/mechanical/articles/50158.aspx

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Thistypeofsystemismoreusefulforlargebuildingscomprisingofanumberoffloors.Ithasthe

plantroomwherealltheimportantunitslikethecompressor,condenser,throttlingvalveandthe

evaporatorarehoused.Theevaporatorisashellandtube.OnthetubesidetheFreonfluidpassesat

extremelylowtemperature,whileontheshellsidethebrinesolutionispassed.Afterpassingthroughthe

evaporator,thebrinesolutiongetschilledandispumpedtothevariousairhandlingunitsinstalledat

differentfloorsofthebuilding.Theairhandlingunitscomprisethecoolingcoilthroughwhichthechilled

brineflows,andtheblower.

Theblowersuckshotreturnairfromtheroomviaductsandblowsitoverthecoolingcoil.Thecool

airisthensuppliedtothespacetobecooledthroughtheducts.Thebrinesolutionwhichhasabsorbed

theroomheatcomesbacktotheevaporator,getschilledandisagainpumpedbacktotheairhandling

unit.Tooperateandmaintaincentralairconditioningsystemsweneedtohavegoodoperators,

techniciansandengineers.Properpreventativeandbreakdownmaintenanceoftheseplantsisvital.

Figure5,showingcontrolpanel,compressor,condenserandaccessories

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Figure6,ShowingviewofAirConditioningPlantRoom

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Figure7,ShowingoveralllayoutofAirConditioningSysteminamultistorybuilding

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Aircycle

Figure8,ShowingoveralllayoutofAirConditioningDuctSysteminamultistorybuilding

Indoorairmaybetoocold,toohot,toodry,toowet,toodraftyortoostill.Theseconditionsare

changedbyrotatingtheairandthesetreatmentsareprovidedintheairconditioningaircycle.

Airdistribution systemdirects the treated air from the air conditioning equipment to the space tobe

conditionedandthenbacktotheequipment.Themaincomponentsintheaircycleare

(i)Fan (ii)Supplyduct

(iii)SupplyOutlets (iv)Returnoutlets

(v)Returnduct (vi)Filter

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(vii)Coolingcoil(orheatingcoilforlowtemperatureareas).

Thetotalresistanceofthesecomponentstotheflowoftheairplusthefrictionresistancecaused

bytheairpassingthroughtheductrunaremajorfactorsindeterminingthesizeofthefanandfanmotor

andtheamountofairpressurethatisrequired.

ForaBroadcastStudiosetupthisresistanceisoftheorderof25mmto50mmofwatergauge.

Centrifugalfanismostcommonlyusedincommercialandresidentialinstallations.Itconsistsofascroll,a

shaftandawheel.Thescrollisactuallyahousingfortheshaftandwheelandtheshaftservesasanaxle

forthewheel.Thewheel iscylindrical inshapeandhasmanyblades.Centrifugalfansareavailablewith

forwardorbackwardcurvedblades.Aforwardcurvedfancandeliverarequiredquantityofairatlowfan

speed.Theairvelocityandspeedofthefanwheel(tipspeed)notonlyplayalargepartindeterminingthe

efficiencyofthefanbutalsoaffectthelevelofnoisegeneratedbythefan.Hightipspeedandhighvelocity

usuallyresultinmorenoise.

Remotelocationofthefanreducesthenoisebutthesystembecomemoreexpensive.Ductsmay

becircular,rectangularorsquareinshape.Fromtheappearanceandpracticalpointofview,rectangular

ductsare

generally

adopted.

Ducts

are

fabricated

from

awide

variety

of

materials.

Ducts

made

of

sheet

metalareverycommon.Theductsare linedwithglasswoolormineralwoolslabsof25mm thickness

wrappedincoppernaphthanatetreatedcloth.

Outletsareanothermajorpartoftheairdistributionsystem.Theyareimportantfromthepointof

viewofappearance,functionsandperformance.Theprimaryfunctionoftheoutletsistoprovideproperly

controlleddistributionofairtotheroomandremovingtheairfromtheroom.

Ceilingdiffusers,grillesandregistersareusedassupplyoutletandgrillesareusedasreturnoutlets.

Operation

Beforestartingtheplant,ensurethatproperfunctioningofsafetycontrolsincludinginterlockcircuithave

beencheckedandcorrectlyset,andthatallmotorsaremeggertested,directionofrotationverified,all

bearingslubricatedandrefrigerationsystemfullycharged.Thecrankcaseheatermustbeenergisedwell

inadvance.

Proceedstepbystepforoperatingthesystemasfollows:

Starttheairhandlingunit,ensuringthatdampersinthesupplyductarefullyopen.

Openallwatervalvesandstartthewaterpump.Observepressuresatcondenserinletandoutlet.

Open hotgas valve on the condenser and the discharge service valve on the compressor.Open

discharge

gauge

valve

to

read

the

pressure.

Followthesameprocedureandreadthesuctionpressure.

Openliquidlinevalve.Observestandingpressureonthegauges.Thisshouldbeapproximately7.03

kg/cm2

(100psi)forR12and10.5kg/cm2

(150psi)forR22toindicatethatthesystemistightwith

noleakage.

Open suction service valve and start the compressor.Observe the refrigerant and oil pressures.

Checkthecurrentdrawnbythecompressormotor,observetheoil level inthecompressorsight

glass.Oilshouldbeclearwithoutfoamafteroperationhasstabilised.

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CompressorPumpDown

It isessential tocollect the refrigerant in thecondenserwith isolation toprevent its lossbefore

opening the compressoror anyotherpartof the system.This is calledpumpdown and theoperation

involvesthefollowingprocedure:

Shortthe lowpressureswitchwithatemporaryjumperwiresothatthecompressordoesnotstop

beforethe

refrigerant

from

it

is

emptied.

Slowlyclosethesuctionvalvewiththecompressorrunning.

Whenthesuctionpressuredropstoabout0.15kg/cm2

(2psi),stopthecompressor.

Neverpumpthecompressorbelow0.15kg/cm2

topreventinfiltrationofmoistureanddirtintothe

crankcase.

Afterafewminutes,thedissolvedrefrigerantwillleavethecrankcaseraisingthesuctionpressure.

Thisadditionalrefrigerantcanbepumpedtothecondenserbyoperatingthecompressoragainfor

ashortwhile.

Repeattheaboveproceduretillthesuctionpressuredoesnotriseabove0.15kg/cm2

afterclosing

theservice

valves.

RemovingRefrigerantfromtheSystem

Itmaybenecessarytoremovetherefrigerantfromthesystemintoacylinderifthereisanexcesscharge

orthereisaleakinthecondenser.Takethefollowingstepsforthisoperation:

(a) Connect a suitable line between the angle valve provided for charging and an empty refrigerant

cylinder.

(b)Purgetheairfromtheconnectionline.

(c)Keep

the

cylinder

cold

by

immersing

it

in

ice

cold

water

to

ensure

afaster

refrigerant

flow

from

the

system.

(d) Start the compressor and open the liquid line charging valve, allowing the liquid into the empty

cylinder. If excess refrigerant is to be removed, hold the charging valve open only until the

dischargepressurereachesthenormalreading.Afterthisoperation,removethecharginglineand

closethechargingvalve.

Donotoverchargethecylinderasexcessivepressureisdangerous.

PurgingNonCondensibleGases

Presenceofnoncondensiblesgasessuchasaircauseshighdischargepressure,resulting inreductionof

capacityandhighpowerconsumption.Incasesuchsymptomsarepresent,thefollowingcheckshouldbe

done:

Shutdownthesystemovernight,longenoughforthetemperatureofallcomponentstoleveloff.

Readthestandingpressureandcompareitwiththerefrigerantsaturationpressurecorrespondingto

the temperatureofthesystem. Ifthestandingpressureexceedsthesaturationpressureby0.75

kg/cm2

(10psi)ormore,thenoncondensiblesareexcessiveandmustberemoved.

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Forexample, ifR22 isusedandthesystemtemperature is85o

F(29.4o

C)andstandingpressure is12.8

kg/cm2

(175psi),thenthereisexcessofnoncondensibles.SaturationpressureforR22correspondingtoa

temperature85o

Fis11kg/cm2

.Thedifferenceis1.05kg/cm2

morethan0.75kg/cm2

,indicatingcorrective

purging.Forpurging,takethefollowingsteps:

Pumpdownthesystemasdescribedearlier.

Immediately

after

stopping

the

compressor,

close

the

compressor

discharge

valve.

Runthewaterthroughthecondensorforcondensationofrefrigerantvapour.

Crackopenthepurgevalveonthetopofthecondensorforaninstant,shutitagain.

Allow the system to stabilize for a fewminutes before reopening and closing the purge valve.

Repeatedpurgingandclosingoperationshouldclearthesystemofnoncondensible.

Restorenormalsystemoperation,checkthe improvement indischargepressure.Checkrefrigerant

chargeandcompressoroilpressure.

RefrigerantCharging

Acorrect

operating

charge

of

refrigerant

in

the

system

is

essential.

Loss

due

to

leakage

in

the

systemhas tobemadeup. Itmaybenecessary to replace theentirecharge.Anovercharge results in

undulyhigh temperatures,pressuresandoperatingcostsandmaydamage thesystemcomponents.An

undercharged system leads to insufficient cooling, high operating cost, and, in hermetic system, the

compressormotormayfail.

Refrigerantmaybeaddedtothesystemeitherasavapourorliquiddependinguponthelocation

of charging point and quantity required. Generally, for adding makeup refrigerant, vapour charging

method ismoreconvenient.Fortotalsystemcharge, liquidchargingatthehighsidefollowedbyvapour

chargingatcompressorlowsidewillbequicker.

Under no circumstances should liquid refrigerant be allowed to enter the compressor to avoid

damagetothecompressor.Theprocedureforvapourchargemethodisdescribedbelow:

Openthesuctionanddischargeshutoffvalvesofthecompressor. Installagauge inthedischarge

gaugeportandopenthegaugelineifagaugeporthasnotbeenprovided.

Connecta refrigerant cylinderand theconnectionwitha compoundgauge, to the chargingvalve

providedoncompressorsuctionline.Purgetheairfromthelinesandtightentheconnections.

Admit the refrigerant by slowly opening the refrigerant cylinder. The cylinder should be kept in

uprightpositiontopreventtherefrigerantfromenteringthecompressorinliquidstate.

Start

the

compressor.

Asthecylindergetsemptied, itspressurewilldropto thesame levelasthesuctionpressure.The

remaining refrigerant canbedrawn from the cylinderby closing the suction shutoff valve and

pullingavacuumonthecylinderwiththecompressorrunning.

Checkthequantityofrefrigerantchargebynotingthedifference intheweightofthecylinderand

observingthepressure.

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WaterTreatment

Algae/slime scale and corrosionon thewater sideof theheat transfer equipment retardsheat

transfer causing general loss of efficiency and breakdowns. Oxygen, Carbon Dioxide, Sulphur Dioxide

absorbed from theairanddissolved inwatercausecorrosion,reducing thecapacityof lines, increasing

frictionallossesandpumpingcost.Hardwatercausesscalingproblem.Whenheated,themineralsareleft

behind,whichformadepositontheheatexchangersurface.Theheattransferratingofthescaleisvery

much lower thanmetal.Retardedheat transfer results in increased dischargepressure causing loss in

capacityandincreasedpowerconsumption.

Scalingofthecondensortubesinarecirculatedwatersystemisunavoidable.Descalinghastobe

carriedoutasapreventivemaintenanceonceevery12monthsorearlierdependingonthehardnessof

thewater.Descalingcanbecarriedoutquiteconvenientlybycirculatingmildinhibitedacidsolutionwith

thehelpofasmallpumpconnectedacrossthecondensorinletandthewatervalvesareclosedtoconfine

thecirculationtothecondenseronly.

Chemical compounds are available which suspend minerals of dissolved scale. Algae attach

themselvesto

the

surfaces,

and

since

they

are

living

plants,

they

grow

until

they

clog

the

passages

of

the

system. Bacteria forms slime and close the system in much the same way as algae. Algae/Slime is

controlledbyuseoftoxic.Aspecialistshouldbeconsultedtodeterminethealgae/slime.

Thetroubleshouldbediagnosedasaccuratelyaspossiblebeforeanyrepairisattempted.Definite

symptomswillaccompanyafaultyoperationinthesystem.Thefollowingtroubleshootingchartwillhelp

infaultlocationandpromptcorrection:

********

TONNAGE MEASUREMENT OF AC PLANTS

(I) By air-flow method

Tonnage of refrigeration (TR) = A x V x (H1 - H2) {FPS units}S 200

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Where

A = Cross sectional area of duct through which air is passing in sq. ft.V = Air velocity per minute, in Ft. per minute, measured by anemometer in

ft./minS = Specific volume of (return) airH1 = Enthalpy for return air, in Btu/lb

H2 = Enthalpy for supply air, in Btu/lb

Note:Both H1 andH2 are determined from the psychometric chart with help of Dry bulbtemperature (Tdb in deg F.) and Wet bulb temperature (Twb in deg F.) SimilarlySpecific volume (S) is determined from the psychometric chart

Example 1:

Calculate Tonnage of AC Plant having the following measurement figures:A = 30.25 sq. ft.

V = 293 Ft. per minuteS = Specific volume of return air = 13.7 cubic Ft./ Lb.

For Return duct,Tdb = 73

0F and Twb = 670 F. ------------- (X)

For Supply duct,Tdb = 53

0F and Twb = 490 F. ------------- (Y)

Calculations:

H1 = Enthalpy for return air, in Btu/ Lb, determined from psychometric chart in r/o(X)

= 31.8 Btu/Lb.H2 = Enthalpy for supply air, in Btu/ Lb, determined from psychometric chart in r/o(Y)

= 19.8 Btu/Lb.S = Specific volume of return air = 13.7 cubic Ft./ Lb.

Therefore Tonnage = Tonnage of refrigeration = A x V x (H1 -H2)TRS 200

= Tonnage of refrigeration = 30.25x293 x (31.8 19.8) TR13.7 200

= 38.8 TR (Answer)

(II) By Water-flow method

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Points to be remembered:

1Watt = 0.86 k Cal / Hr** (unit of power i.e. rate of energy)

1 Watt = 3.412 Btu / Hr* or [1 Btu = 1 3.412 Watts]

1 k Watt = 3412 Btu / Hr or [1 Btu = 1 3412 k Watts] #

1 Btu = 0.252 k Cal

1 Ton = 12000 Btu / Hr

= 200 Btu / Min

= 50 k Cal / Min [200 Btu x 0.252 k Cal]

= 3024 k Cal / Hr [200 Btu x 0.252 k Cal x 60 Min]

= 3.561 kW # [12000 3412 = 3.561]

Heat gained by water = { Q x Sp. Heat x (Th Tc) x 60} Btu/Hr ---- (A)= heat rejected by the refrigerant in the condenser

Heat developed due to work done by compressor ={ 3 V x I x Cos }Watts= { 3 V x I x Cos x 3.412}*Btu/Hr ----- (B)Or= { 3 V x I x Cos x 0.86} ** k Cal /Hr

Refrigeration capacity in TR =[Heat gained by water in Btu/Hr] [Heat developed due to work done by compressor in Btu/Hr]

12000= (A) - (B)

12000

= { Q x Sp. Heat x (Th Tc) x 60} { 3 V x I x Cos x 3.412}12000

Where Q = Quantity of water flowing through the water cooled condenser in Ltr/ Min

Th = Temperature after condenser in0

FTc = Temperature before condenser in 0 F

Sample measurements

Q = Quantity of water flowing through the water cooled condenser = 620 Ltr/ MinTh = Temperature at condenser outlet = 990 F

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Tc = Temperature at condenser inlet = 92 FV = compressor Voltage = 390 VoltsI = compressor Current = 60 AmpCos = Power Factor = 0.85

Calculations:(A) = Heat rejected by the refrigerant in the condenser

= Q x Sp. Heat x (Th Tc) x 60 Btu/Hr= 620 x 2.204 x (99 92) x 60 = 57,3922 Btu/Hr

(B) = Heat developed due to work done by compressor

= { 3 V x I x Cos x 3.412} Btu / Hr= { 3 x 390 x 60 x .85 x 3.412} Btu / Hr = 11, 7476 Btu / Hr

Refrigeration capacity in TR = (A) - (B) = (57,3922) - (11,7476) = 38 TR, ANSWER 12000 12000

***********

HVAC AirConditioningTroubleshootingandRepair

ThefollowingisangeneralA/Csystemtroubleshootingguide.Realizethatitisgenericandmanyofthe

thingslisted

here

may

not

apply

to

the

944.

Symptom/PossibleCause Solutions

LowCompressorDischargePressure

1.Leakinsystem

2.Defectiveexpansionvalve

3.Suctionvalveclosed

4.Freonshortage

5.Pluggedreceiverdrier

Repair

1.Repairleakinsystem

2.Replacevalve

3.Openvalve

4.Addfreon

5.Replacedrier

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6.Compressorsuctionvalveleaking

7.Badreedvalvesincompressor

6.Replacevalve

7.Replacereedvalves

HighCompressorDischargePressure

1.Airinsystem

2.Cloggedcondenser

3.Dischargevalveclosed

4.Overcharged

system

5.Insufficientcondenserair

6.Loosefanbelt

7.Condensernotcenteredonfanortoofarfrom

radiator

Repair

1.Rechargesystem

2.Cleancondenser

3.Open

valve

4.Removesomerefrigerant

5.Installlargefan

6.Tightenfanbelt

7.Centerandcheckdistance

LowSuctionPressure

1.Refrigerantshortage

2.Worncompressorpiston

3.Compressorheadgasketleaking

4.Kinkedorflattenedhose

5.Compressorsuctionvalveleaking6.Moistureinsystem

7.Trashinexpansionvalveorscreen

Repair

1.Addrefrigerant

2.Replacecompressor

3.Replaceheadgasket

4.Replacehose

5.Changevalveplate6.Replacedrier

7.Replacedrier

HighSuctionPressure

1.Looseexpansionvalve

2.Overchargedsystem

3.Expansionvalvestuckopen

4.Compressorreedvalves

5.Leakingheadgasketoncompressor

Repair

1.Tightenvalve

2.Removesomerefrigerant

3.Replaceexpansionvalve

4.Replacereedvalves

5.Replaceheadgasket

CompressorNot

Working

1.Brokenbelt

2.Brokenclutchwireorno12vpower

3.Brokencompressorpiston

4.Badthermostat

5.Badclutchcoil

6.LowRefrigerant lowpressureswitchhascut

offclutchpower

Repair

1.Replacebelt

2.Repairwireorcheckforpower

3.Replacecompressor

4.Replacethermostat

5.Replaceclutchcoil

6.Addrefrigerant

EvaporatorNotCooling

1.Frozencoil,switchsettoohigh

2.Drive

belt

slipping

3.Hotairleaksintocar

4.Pluggedreceiverdrier

5.Capillarytubebroken

6.Shortageofrefrigerant

7.Highheadpressure

8.Lowsuctionpressure

9.Highsuctionpressure

Repair

1.Turnthermostatswitchback

2.Tighten

belt

3.Checkforholesoropenvents

4.Replacedrier

5.Replaceexpansionvalve

6.Addrefrigerant

7.Seeproblem#2

8.Seeproblem#3

9.Seeproblem#4

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10.Defectiveexpansionvalve

11.Frozenexpansionvalve

10.Replaceexpansionvalve

11.Evacuateandreplacedrier

FrozenEvaporatorCoil

1.Faultythermostat

2.Thermostatnotsetproperly

3.Insufficient

evaporator

air

Repair

1.Replacethermostat

2.Settodrivingcondition

3.Checkforexcessiveducthoselength,

kinkor

bend.

ACSystemGaugeReadings

ThefollowingtableisageneralguidelineforA/Csystempressuresandtemperaturesbasedonambient

outsidetemperature.Rememberthattheseareaguidelineandyouractualtemperaturesandpressures

willvarydependingonhumidityintheairandtheconditionofyoursystem.

A/CSystemPressureReadings

AmbientTemperature

Low

Side

Pressure

High

Side

Pressure

Center

Vent

Temperature

60F 2838psi 130190psi 4446F

70F 3040psi 190220psi 4448F

80F 3040psi 190220psi 4348F

90F 3540psi 190225psi 4450F

100F 4050psi 200250psi 5260F

110F 5060psi 250300psi 6874F

120F 5565psi 320350psi 7075F

*********