Installation Guide
69-2271EFS—01 12
Problem Recommended Troublshooting Steps
Nodehumidification,neither
impeller fan nor compressor run
with fan switch and ventilation
timerOFF.
1. Unitunpluggedornopowertooutlet.
2. Humidity control set too high or defective.
3. Loose connection in internal or control wiring.
4. DefectiveCompressorrelay.
5. Defectivecontroltransformer.
6. Low pressure Control open.
7. OptionalCondensatePumpSafetySwitchopen.
Nodehumidification,compressor
doesnotrunbutimpellerfanruns
with fan switch and ventilation
timerOFFandhumiditycontrol
turnedtoON.
1. Defectivecompressorruncapacitor.
2. Badconnectionincompressorcircuit.
3. Defectivecompressoroverload.
4. Defectivecompressor.
5. Defrostthermostatopen.
Impellerfanrunswithfanswitch
andventilationtimerOFF,but
compressor cycles on & off.
1. Lowambienttemperatureand/orhumiditycausingunittocyclethrough
defrost mode.
2. Defectivecompressoroverload.
3. Defectivecompressor.
4. Defrostthermostatdefective
5. Dirtyairfilter(s)orairflowrestricted.
6. Lowrefrigerantcharge,causingdefrostcontroltocycle.
7. Badconnectionincompressorcircuit.
CAUTION:ServicingtheTrueDRYDH150withitshighpressurerefrigerantsystemandhighvoltagecir-
cuitrypresentsahealthhazardwhichcouldresultindeath,serious bodilyinjury,and/orpropertydamage.
Serviceshouldonlybeperformedbyaqualifiedservice technician.
Technical DescriptionTroubleshooting
TrueDRYDH150usesarefrigerationsystemsimilartoanaircondi-
tioner to remove heat and moisture from incoming air and add heat
totheairthatisdischarged.Hot,high-pressurerefrigerantgasis
routedfromthecompressortothecondensercoil.Therefrigerantis
cooledandcondensedbygivingupitsheatto theairthatisabout
tobedischargedfromtheunit.Therefrigerantliquidthenpasses
throughastrainerandcapillarytubingwhichcausestherefrigerant
pressureandtemperaturetodrop.Itnextenterstheevaporatorcoil
whereitabsorbsheatfromtheincomingairandevaporates.The
evaporatoroperatesinafloodedcondition,whichmeansthat allthe
evaporatortubescontainliquidrefrigerantduringnormaloperation.
Afloodedevaporatorshouldmaintainnearlyconstantpressureand
temperatureacrosstheentirecoil,frominlettooutlet.
Themixtureofgasandliquidrefrigerantentertheaccumulatorafter
leavingtheevaporatorcoil.Theaccumulatorpreventsanyliquid
refrigerantfromreachingthecompressor.Thecompressorevacuatesthecoolrefrigerantgasfromtheaccumulator
and compresses it to a high pressure and temperature to repeat the process.
CONDENSER
EVAPORATOR
CAPILLARY
TUBES
ACCUMULATOR
COMPRESSOR
STRAINER/FILTER
DRIER
M27404