Mitsubishi PUZ-A18NHA6 - Page 36

36
Thermistors
Open detection Short detection
Symbol Name
TH3
TH6
TH7
TH8
−58°F [−50:] or below
194°F [ 90:] or above
216°F [102:] or above
Thermistor <Liquid>
Thermistor <2-phase pipe>
Thermistor <Ambient>
Thermistor <Heat sink>
−58°F [−50:] or below
−58°F [−50:] or below
−54°F [−48:] or below
TH33 Thermistor <Suction>
194°F [ 90:] or above
194°F [ 90:] or above
−58°F [−50:] or below
194°F [ 90:] or above
Check code
Abnormal point and detection method
Case
Judgment and action
U5
(4230)
Temperature of heat sink
Abnormalifheatsinkthermistor(TH8)
detectstemperatureindicatedbelow.
A12,18,42N·············183˚F[84:]
A24,30,36N·············177˚F[81:]
1Theoutdoorfanmotoris
locked.
2Failureofoutdoorfanmotor
3Airflowpathisclogged.
4Riseofambienttemperature
5Defectivethermistor
6Defectiveinputcircuitof
outdoorpowercircuitboard
7Failureofoutdoorfandrive
circuit
12Checkoutdoorfan.
3Checkairflowpathforcooling.
4Checkifthereissomethingwhichcauses
temperaturerisearoundoutdoorunit.
(Upperlimitofambienttemperatureis114˚F
[46:].)
Turnoffpower,andonagaintocheckifU5
isdisplayedwithin30minutes.
IfU4isdisplayedinsteadofU5,followthe
actiontobetakenforU4.
5Checkresistancevalueofthermistor(TH8)
ortemperaturebymicroprocessor.
 (Thermistor/TH8:Referto"10-6.HOWTO
CHECKTHEPARTS".)
 (SW2onA-ControlServiceTool:Refer
to"10-10.FUNCTIONOFSWITCHES,
CONNECTORSANDJUMPERS".
6Replaceoutdoorpowercircuitboard.
7Replaceoutdoorcontrollercircuitboard.
U3
(5104)
Open/short circuit of outdoor unit
temperature thermistor (TH32)
Abnormalifopen(37˚F[3:]orless)or
short(422˚F[217:]ormore)isdetected
duringcompressoroperation.
(Detectionisinoperativefor10minutes
ofcompressorstartingprocessandfor10
minutesafterandduringdefrosting.)
TH32:Thermistor<Comp.surface>
1Disconnectionorcontactfailure
ofconnectors(TH32)on
theoutdoorcontrollercircuit
board
2Defectivethermistor
3Defectiveoutdoorcontroller
circuitboard
1Checkconnectionofconnector(TH32)onthe
outdoorcontrollercircuitboard.Checkbreak-
ingoftheleadwireforTH32.Referto"10-9.
TESTPOINTDIAGRAM".
2CheckresistancevalueofTH32or
temperaturebymicroprocessor.
(Thermistor/TH32:Referto"10-6.HOWTO
CHECKTHEPARTS".)(SW2onA-Control
ServiceTool:Referto"10-10.FUNCTION
OFSWITCHES,CONNECTORSAND
JUMPERS".)
3Replaceoutdoorcontrollerboard.
U4
(TH3:5105)
(TH6:5107)
(TH7:5106)
(TH8:5110)
(TH33:5133)
Open/short of outdoor unit thermistors
(TH3, TH6, TH7, TH8 and TH33 )
Abnormalifopenorshortisdetected
duringcompressoroperation.
OpendetectionofthermistorsTH3and
TH6isinoperativefor10secondsto10
minutesaftercompressorstartingand10
minutesafterandduringdefrosting.
Note:Checkwhichunithasabnormalityin
itsthermistorbyswitchingthemode
ofSW2.(PAC-SK52ST)(Referto
"10-10.FUNCTIONOFSWITCHES,
CONNECTORSANDJUMPERS".)

1Checkconnectionofconnector(TH3,TH6/TH7,
TH33)ontheoutdoorcontrollercircuitboard.
 Checkconnectionofconnector(CN3)onthe
outdoorpowercircuitboard.
 Checkbreakingoftheleadwireforthermis-
tor(TH3,TH6,TH7,TH8,TH33).Referto"10-
9.TESTPOINTDIAGRAM".
2Checkresistancevalueofthermistor
(TH3,TH6,TH7,TH8,TH33)orchecktem-
peraturebymicroprocessor.
 (Thermistor/TH3,TH6,TH7,TH8,TH33:Refer
to"10-6.HOWTOCHECKTHEPARTS".)
 (SW2onA-ControlServiceTool:Refer
to"10-10.FUNCTIONOFSWITCHES,
CONNECTORSANDJUMPERS".)
3Replaceoutdoorcontrollercircuitboard.
Note:Emergencyoperationisavailableincase
ofabnormalitiesofTH3,TH6,TH7and
TH33.Referto"10-8.EMERGENCY
OPERATION".
1Disconnectionorcontactfailure
ofconnectors
 Outdoorcontrollercircuit
 board:TH3,TH6/TH7,TH33
 Outdoorpowercircuitboard:
CN3
2Defectivethermistor
3Defectiveoutdoorcontroller
circuitboard
(
)
U6
(4250)
Power module
Checkabnormalitybydrivingpowermodule
incaseovercurrentisdetected.
(UForUPerrorcondition)
1Outdoorstopvalveisclosed.
2Decreaseofpowersupplyvoltage
3Looseness,disconnectionor
converseofcompressorwiring
connection
4Defectivecompressor
5Defectiveoutdoorpowercircuit
board
1Openstopvalve.
2Checkfacilityofpowersupply.
3Correctthewiring(U·V·Wphase)to
compressor.Referto"10-9.TESTPOINT
DIAGRAM"(Outdoorpowercircuitboard).
4Checkcompressorreferringto"10-6.HOW
TOCHECKTHEPARTS".
5Replaceoutdoorpowercircuitboard.
OCH577A