Carrier 38AU appendix Problem Solution Compressor Cycles on LOW-PRESSURE Switch, System is Noisy

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TROUBLESHOOTING (cont)

	PROBLEM		SOLUTION

COMPRESSOR CYCLES ON LOW-PRESSURE SWITCH
Indoor-Air Fan Running
1.	Liquid line solenoid valve(s) fails to open.	1. Check liquid line solenoid valve(s) for proper operation. Replace if necessary.
2.	Filter drier plugged.	2.	Replace filter drier.
3.	Expansion valve power head defective.	3.	Replace power head.
4.	Low refrigerant charge.	4.	Add charge. Check low-pressure switch setting.
Airflow Restricted
1.	Coil iced up.	1.	Check refrigerant charge.
2.	Coil dirty.	2.	Clean coil fins.
3.	Air filters dirty.	3.	Clean or replace filters.
4.	Dampers closed.	4.	Check damper operation and position.
Indoor-Air Fan Stopped
1.	Electrical connections loose.	1.	Tighten all connections.
2.	Fan relay defective.	2.	Replace relay.
3.	Motor overload open.	3.	Power supply.
4.	Motor defective.	4.	Replace motor.
5.	Fan belt broken or slipping.	5.	Replace or tighten belt.

COMPRESSOR RUNNING BUT COOLING INSUFFICIENT
Suction Pressure Low
1.	Refrigerant charge low.	1.	Add refrigerant.
2.	Head pressure low.	2.	Check refrigerant charge. Check outdoor-air fan thermostat settings.
3.	Air filters dirty.	3.	Clean or replace filters.
4.	Expansion valve power head defective.	4.	Replace power head.
5.	Indoor coil partially iced.	5.	Check low-pressure setting.
6.	Indoor airflow restricted.	6.	Remove obstruction.
Suction Pressure High
1.	Heat load excessive.	1.	Check for open doors or windows in vicinity of fan coil.

UNIT OPERATES TOO LONG OR CONTINUOUSLY
1.	Low refrigerant charge.	1.	Add refrigerant.
2.	Control contacts fused.	2.	Replace control.
3.	Air in system.	3.	Purge and evacuate system.
4.	Partially plugged expansion valve or filter drier.	4.	Clean or replace.

SYSTEM IS NOISY
1.	Piping vibration.	1.	Support piping as required.
2.	Compressor noisy.	2.	Replace compressor if bearings are worn.

COMPRESSOR LOSES OIL
1.	Leak in system.	1.	Repair leak.
2.	Crankcase heaters not energized during shutdown.	2.	Check wiring and relays. Check heater and replace if defective.
3.	Improper interconnecting piping design.	3.	Check piping for oil return. Replace if necessary.

FROSTED SUCTION LINE
Expansion valve admitting excess refrigerant.		Adjust expansion valve.

HOT LIQUID LINE
1.	Shortage of refrigerant due to leak.	1.	Repair leak and recharge.
2.	Expansion valve opens too wide.	2.	Adjust expansion valve.

FROSTED LIQUID LINE
1.	Restricted filter drier.	1.	Remove restriction or replace.
2.	Liquid line solenoid valve partially closed.	2.	Replace valve.

38AU

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Contents Contents Installation, Start---Up Service InstructionsSafety Considerations Installation GuidelineReplacement/Retrofit R-22 to PuronR Unit Damage Hazard InstallationUnit MchxRtpf 38AUD*25 38AUZ*25Refrigerant TYPE‡ Unit Size 38AUCompressor Condenser FansNominal Capacity kW Pressurestat Settings kPa High CutoutRtpf Shipping Charge kg ScrollRtpf Shipping Charge A/B lb Oil Charge A/B ozFace Area sq ft total Rows/Fins per inch FPI Rtpf Shipping Charge A/B kg Operating Weight kg Novation Coil Al TubeOil Charge A/B L Qty...r/s Motor Hp Nema Diameter mmU Z a 2 5 a 0 G 6 a 0 a 0 a Matching 38AU Model To Evaporator Coil InstallationJobsite Survey Do not Bury Refrigeration LinesSlab Mount Provide Safety ReliefEquivalent Lengths for Common Fittings ft Check 38AU Model with Evaporator Coil ConnectionsLiquid Lift Suction Riser38AUZ 16-25 Piping Recommendations Single-Circuit Unit Vertical Separation outdoor unit above indoor unit 38AUD 16-25 Piping Recommendations Two-Circuit UnitInsulate Suction Lines Hot Gas BypassRefrigerant Specialties Part Numbers Install Filter Driers and Moisture IndicatorsCapacity Control Liquid Line Solenoid Valve Install Liquid Line Solenoid ValveSelecting an Accumulator Make Piping ConnectionsPreliminary Charge Evacuation/DehydrationUnits with Factory-Installed Disconnect Field Power SupplyFire Hazard All UnitsElectrical Operation Hazard Convenience OutletsConvenience Outlet Utilization Notice Label Field Control WiringThermostat Control Transformer WiringUnbalanced 3-Phase Supply Voltage Unit Wire/Fuse or Hacr Breaker Sizing DataSTART-UP PRE-START-UPSystem Check Preliminary ChecksAdjust Refrigerant Charge Advanced Scroll Temperature Protection AstpUsing plotted operating point Start UnitFinal Checks 38AUZ*25 Check Compressor Oil Level38AUD*16 Charging Chart Novation 38AUZ*16 Charging Chart Rtpf 38AUD*16 Charging Chart Rtpf 38AUD*25 Charging Chart Rtpf Typical 38AUZ Wiring Diagram 15 Ton 230V Tandem Unit Shown Typical 38AUD Wiring Diagram 15 Ton 230V Dual Unit Shown Base Unit Controls Operating SequenceService Routine System MaintenanceRefrigeration System Equipment Damage HazardField Refrigerant Access Ports Factory High-Flow Access PortsLiquid Line Filter Drier Input Terminal Voltage Comfort Alert Diagnostic ModuleLockout LED Status CodesCompressor Protection 38AUD Size 16 Cabinet LPS 38AUZ,D Size 25 Cabinet 38AUZ*25 Compressor Assembly Rear View Repairing Novation Condenser Tube Leaks Novation Coil Cleaning and MaintenanceCoil Type Identification NOVATIONt TypeRoutine Cleaning of Round-Tube Plate Fin Rtpf Coils Replacing NOVATIONt Condenser CoilUnit Reliability Hazard Problem Solution Compressor does not RUN TroubleshootingCompressor Stops on HIGH-PRESSURE Switch Fastener Torque ValuesCompressor Running but Cooling Insufficient Problem Solution Compressor Cycles on LOW-PRESSURE SwitchUnit Operates TOO Long or Continuously System is NoisyWiring Diagram List Appendix aAppendix B Troubleshooting Low Ambient Option Factory InstalledAppendix C Operation38AUZ*16 & 38AUD*16 Novation 38AUZ*16/25 & 38AUD*16/25 Rtpf Motormaster Sensor LocationWind Baffle Dimension Dimensions --- Inches Unit BaffleDimensions --- MM Unit Baffle Wind Baffles Fabrication 15 Ton Wind Baffle Brackets Fabrication Front Front Back Left Right Catalog No 38AU---09SI II. PRE-START-UP Outdoor Unit START-UP ChecklistCheck Voltage Imbalance