Multi-Split Systems - McQuay

Generally, there are two kinds of common problems, i.e. starting failure and insufficient cooling. "Starting failure"is caused by electrical defect while "insufficient cooling" is caused by improper application or defects inrefrigerant circuit.DIAGNOSIS OF STARTING FAILUREStarting failureOutdoor unit does notoperate at allPreliminary causes :-- Voltage not within +/- 10% or rated- Temperature setting improper- Wiring disconnectedCheck power sourceCheck inputsignal fromindoor tooutdoor unitYesNoCheck fuse and circuitbreaker and powercordCheck indoor unitNoPCB controllerin outdoor unitfunctioningYesTransformerdefectiveNoChecksecondaryside of powertransformerCheck compressor orfan motor• Loose connection• Capacitor defective• Compressor or fanmotor defectiveOKPCB defectiveDIAGNOSIS OF INSUFFICIENT COOLINGInsufficient coolingInsufficient coolingInsufficient coolingRefrigerant circuitAir circulationCompressorExcessive heat sourcee.g. electric kettleLeakage or insufficientchargeIndoor/outdoor coildirty (clogged)Less or nocompression (lowrunning current)Room over-crowedwith peopleRestriction at strainer,capillary, etc.Air filter dirtyWindows/doors wideopenFan malfunctionObstruction at air inlet/outlet of indoor/outdoor unit217