Symptom Possible Cause
Corrective Action
)JHITVDUJPO
pressure
&YDFTTJWFMPBEPOFWBQPSBUPSDPJM
$IFDLGPSIJHIFOUFSJOHXFUCVMCUFNQFSBUVSFDIFDLGPS
FYDFTTJWFBJSnPX
$PNQSFTTPSJTVOMPBEFE
EJHJUBMTDSPMM
$IFDLEJHJUBMTDSPMMDPOUSPMMFSTJHOBMBOETPMFOPJEWBMWF
&YQBOTJPOWBMWFTFOTJOHCVMCOPU
secured to suction line.
$IFDLUIFUIFSNBMFYQBOTJPOWBMWFFOTVSFCVMCJT
JOTVMBUFE$IFDLTVQFSIFBU*GTVQFSIFBUJTIJHIUIFO
WBMWFJTDIPLJOHSFGSJHFSBOUnPX
t$IFDLCVMCGPSDPOUBDU
t"EKVTUWBMWFGPSTVQFSIFBU_¡'
t3FQMBDFWBMWFQPXFSIFBEPSWBMWF
Thermostatic expansion valve.
Overfeeding.
$IFDLCVMCMPDBUJPOBOEDMBNQJOH"EKVTUTVQFSIFBU
Replace expansion valve power head.
Room load too large.
Reduce the load or add more equipment.
Overcharged.
$IFDLQSFTTVSFTBOETVCDPPMJOH
)JHI
discharge
pressure
Thermal expansion valve setting.
$IFDLUIFSNBMFYQBOTJPOTFUUJOHBOEDBMJCSBUF
TVQFSIFBUøøTVCDPPMJOH
"JSJOMFUUPDPOEFOTFSEJSUZPS
PCTUSVDUFE
$IFDLGPSQSPQFSDMFBSBODFTBOEQPTTJCMFBJS
SFDJSDVMBUJOH$MFBODPJM
$POEFOTFSGBONPUPSEFGFDUJWF
$IFDLDPOEFOTFSGBONPUPS
Too much refrigerant.
$IFDLTVCDPPMJOH3FNPWFFYDFTTSFGSJHFSBOU
/PODPOEFOTBCMFJOTZTUFN
3FNPWFOPODPOEFOTBCMFGSPNTZTUFN
%JSUZDPOEFOTFSDPJM
$MFBODPOEFOTFSDPJM
$POEFOTFSGBOOPUSVOOJOHPSSVOOJOH
CBDLXBSET
$IFDLFMFDUSJDBMDJSDVJUBOEGVTF$IFDLGBODZDMJOH
controls.
)JHIMPBEDPOEJUJPOT
"EENPSFFRVJQNFOUPSSFEVDFMPBE
Low suction
pressure
Refrigerant undercharge/loss of
refrigerant charge.
$IFDLQSFTTVSFTBOETVCDPPMJOH
#MPXFSSVOOJOHCBDLXBSE
$POmSNCMPXFSSPUBUJPO*GSFWFSTFEJOUFSDIBOHFBOZUXP
XJSFTGSPNQIBTFEJTDPOOFDU
Low entering air temperature.
-PXMPBEDPOEJUJPOT
$IFDLFOUFSJOHBJSXFUCVMCDPOEJUJPOT
3FGSJHFSBOUMFBL
$IFDLTZTUFNGPSMFBLT3FQBJSMFBLTBOEBEESFGSJHFSBOU
&WBQPSBUPSEJSUZPSJDFEVQPSBJSnPX
restricted.
$MFBOUIFDPJM$IFDLGBOPQFSBUJPO$IFDLBJSnPX
1MVHHFEMJRVJEMJOFmMUFSESJFS
3FQMBDFmMUFSESJFSDIFDLQTJBDSPTTmMUFS
*NQSPQFSIPUHBTCZQBTTTFUUJOH
$IFDLTFUUJOHBOEDPSSFDUBTSFRVJSFE
&YQBOTJPOWBMWFEFGFDUJWFTVQFSIFBU
too high or valve too small.
"EKVTUWBMWFGPSQSPQFSTVQFSIFBUPSSFQMBDFUIF
expansion valve if too small or defective.
.PJTUVSFJOTZTUFNDIFDLTJHIUHMBTT
3FDMBJNSFGSJHFSBOUDIFDLGPSMFBLTSFDIBSHF
Troubleshooting – Refrigeration Circuit
Always have a completed Pre-Start-Up Checklist and Start-Up Checklist prior to requesting parts or service
information.
24
Packaged Rooftop Ventilator
®
