Carrier Infinity 25VNA0 Service Manual

Also see for Infinity 24VNA0: Owner's manual

32StartVerify motortemp faultcondition at thesystem controllerDisconnect 4-pinplug from drive(See Fig. 18)Measureresistancebetween red &white wires in the4-pin plugIs resistance459Ω to 168KΩ ?YesNoIs resistance459Ω -168KΩ?Allow time forcompressor tocool & resistanceto change (60minutes )Is Ω moving towardsΩ corresponding toambient temp ?Resistanceis in rangethat willallowoperationYesNoMeasureresistancebetween unitground andblack, white, &red wires in theplugIs there continuityto ground ?YesNoIs the systemoperable ? AYesNoBIs compressorhot ?AYesNoMeasureresistancebetween red &white wires in the4-pin plugIs resistance0Ω?Refer tothermistorresistance -temperature data(See Fig. 15)WARNING !Disconnect &lock- out power,allow 2 minutesfor drive todischargeANoYesNoIf problem stillexists, changethe compressorRefer tothermistorresistance -temperature dataYesPower down theentire system for2 minutes toreboot the driveAllow time forresistance tochange (60minutes )WARNING !Recover systemrefrigerantchargeThermistorcircuit isshortedRemove themolded plug fromthe thermistorfusite on thecompressor(See Fig. 19)Measureresistance inmotor thermistorcircuit pins(See Fig. 20 & 21)Is resistance0Ω? YesNoMotor thermistorcircuit is shortedinternally - replacecompressorInspect moldedplug assemblyfor lead to leadshortingInstall newmolded plugassembly andcarefully routewiresACDisconnectyellow, black,and red wiresfrom outputconnections ondrive (See Fig. 23)Verify motorwindingcontinuity fromthe yellow, black,and red leadendsCheck each leg(yellow, black,and red wires) togroundIf any of theabove Ω readingsshow open orshort to ground,replace the plugA11554Fig. 15 – Motor Temp Fault Troubleshooting -- Part 1