Honeywell TRUEDRY DH150 - Troubleshooting

Installation Guide
69-2271EFS—01 12
Problem Recommended Troublshooting Steps
Nodehumidification,neither
impeller fan nor compressor run
with fan switch and ventilation
timerOFF.
1. Unitunpluggedornopowertooutlet.
2. Humidity control set too high or defective.
3. Loose connection in internal or control wiring.
4. DefectiveCompressorrelay.
5. Defectivecontroltransformer.
6. Low pressure Control open.
7. OptionalCondensatePumpSafetySwitchopen.
Nodehumidification,compressor
doesnotrunbutimpellerfanruns
with fan switch and ventilation
timerOFFandhumiditycontrol
turnedtoON.
1. Defectivecompressorruncapacitor.
2. Badconnectionincompressorcircuit.
3. Defectivecompressoroverload.
4. Defectivecompressor.
5. Defrostthermostatopen.
Impellerfanrunswithfanswitch
andventilationtimerOFF,but
compressor cycles on & off.
1. Lowambienttemperatureand/orhumiditycausingunittocyclethrough
defrost mode.
2. Defectivecompressoroverload.
3. Defectivecompressor.
4. Defrostthermostatdefective
5. Dirtyairfilter(s)orairflowrestricted.
6. Lowrefrigerantcharge,causingdefrostcontroltocycle.
7. Badconnectionincompressorcircuit.
CAUTION:ServicingtheTrueDRYDH150withitshighpressurerefrigerantsystemandhighvoltagecir-
cuitrypresentsahealthhazardwhichcouldresultindeath,seriousbodilyinjury,and/orpropertydamage.
Serviceshouldonlybeperformedbyaqualifiedservicetechnician.
Technical Description
Troubleshooting
TrueDRYDH150usesarefrigerationsystemsimilartoanaircondi-
tioner to remove heat and moisture from incoming air and add heat
totheairthatisdischarged.Hot,high-pressurerefrigerantgasis
routedfromthecompressortothecondensercoil.Therefrigerantis
cooledandcondensedbygivingupitsheattotheairthatisabout
tobedischargedfromtheunit.Therefrigerantliquidthenpasses
throughastrainerandcapillarytubingwhichcausestherefrigerant
pressureandtemperaturetodrop.Itnextenterstheevaporatorcoil
whereitabsorbsheatfromtheincomingairandevaporates.The
evaporatoroperatesinafloodedcondition,whichmeansthatallthe
evaporatortubescontainliquidrefrigerantduringnormaloperation.
Afloodedevaporatorshouldmaintainnearlyconstantpressureand
temperatureacrosstheentirecoil,frominlettooutlet.
Themixtureofgasandliquidrefrigerantentertheaccumulatorafter
leavingtheevaporatorcoil.Theaccumulatorpreventsanyliquid
refrigerantfromreachingthecompressor.Thecompressorevacuatesthecoolrefrigerantgasfromtheaccumulator
and compresses it to a high pressure and temperature to repeat the process.
CONDENSER
EVAPORATOR
CAPILLARY
TUBES
ACCUMULATOR
COMPRESSOR
STRAINER/FILTER
DRIER
M27404