Mitsubishi FDT125VNPWVH - (4) Troubleshooting at the outdoor unit

'22 • PAC-SM-412
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(4) Troubleshooting at the outdoor unit
Whentroubleshootingtheoutdoorunit,rstlyassesstheoverviewofmalfunctionandtrytopresumethecauseandthe
faultypartbycheckingtheerrorcodedispalyedontheremotecontrol,andthenproceedfurtherinspectionandremedy
it.
Self-diagnosissystembymicrocomputoronindoorunitandoutdoorunitPCBcanassisttondthecauseofmalfunction
smoothly by making a diagnosis of  not only the anomaly of microcomputer, but also the anomaly in power source
system,installationspace,overloadresultingfromimproperchargingamountofrefrigerantandetc.
Unlessthepowerisreset,theerrorlogissavedinmemoryandtheinspectionindicatorlampsonoutdoorunitPCBkeep
ashingafterautomaticalrecoveringfrommalfunction.
Afterautomaticalrecoveringfrommalfunction,ifanyanothererrormodewhichhasahigherprioritythantheprevious
errorsavedinmemoryoccurs,itisoverwritteninmemoryandisdisplayed.
[Reset of power source]
Besureto avoid electrical shock, when replacingor checkingtheoutdoorunit PCB, because some voltage isstill
retainedintheelectrolyticcapacitoronthePCBevenaftershuttingdownthepowersourcetotheoutdoorunit.
Besuretostartrepairingwork,andreconrmingthatvoltagehasbeendischargedsucientlybymeasuringthevoltage
(DC)betweenbothterminalsofelectrolyticcapacitor(C58)(Measurmentofvoltagemaybedisturbedbythemoisture-
proofcoating.Insuchcase,removethecoatingandmeasureitbytakingcareofavoidingelectricalshock.)
(a) Module of part to be replaced for outdoor unit control
 OutdoorunitPCB,Temperaturesensor(ofoutdoorheatexchanger,dischargepipe,outdoorair),Fuses(forpower
source and main PCB)
(b) Replacement procedure of outdoor unit control PCB
Precautions for Safety
・
Since the following precaution is the important contents for safety, be sure to observe them.
WA RNING and CAUTION are described as follows:
WARNING
Indicates an imminently hazardous situation which will result in death or serious
injury if proper safety procedures and instructions are not adhered to.
CAUTION
Indicates a potentially hazardous situation which may result in minor or moderate
injury if proper safety procedures and instructions are not adhered to.
WARNING
・ Securely replace the PCB according to this procedure.
If the PCB is incorrectly replaced, it will cause an electric shock or fire.
・ Be sure to check that the power source for the outdoor unit is turned OFF before replacing the
PCB. The PCB replacement under current-carrying will cause an electric shock or fire.
・ After finishing the PCB replacement, check that wiring is correctly connected with the PCB before
power distribution. If the PCB is incorrectly replaced, it will cause an electric shock or fire.
CAUTION
・ Band the wiring so as not to tense because it will cause an electric shock.
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