American Standard UV05 manual Space Temp Sensor Failure F0, DX Pressure Fault F1

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Diagnostics and Service

Space Temp Sensor Failure (F0)

The Space Temp Sensor Failure fault occurs when the UVC detects open or short conditions from the sensor.

Effect:

•Space fan de-energizes (unless in emergency heat mode).

•Compressor immediately de-energizes.

•Outdoor fan (if present) de-energizes.

•Outside air damper is forced closed.

•Electric heat stages are de-energized.

•Fault is indicated.

DX Pressure Fault (F1)

The DX Pressure Fault occurs when the UVC detects a switch open condition from the refrigerant pressure switch.

Effect:

•Compressor immediately de-energizes.

•Outdoor fan (if present) de-energizes.

•Fault is indicated.

Compressor Envelope Fault (F2)

The UVC monitors refrigerant temperatures. The Compressor Envelope Fault occurs when the

UVC detects compressor operation that exceeded the allowed operating parameters.

Effect:

•Compressor immediately de-energizes.

•Outdoor fan (if present) de-energizes.

•Fault is indicated.

Cause:

•Poor air or water flow through the refrigerant coils. Check fans for proper rpm. Check air filters.

•If the unit has a three-phase scroll compressor, check for proper electrical phasing.

•Refrigerant circuit component failure or improper adjustment. Check refrigerant pressures and TXV adjustment.

•Coil sensors may have lost proper contact with the refrigerant coil. Check coil sensors.

Discharge Air DX Cooling Low Limit Indication (F3)

The Discharge Air DX Cooling Low Limit Indication fault occurs when the UVC detects a low discharge air temperature (DAT < MCLL) during compressor cooling.

Effect:

•Compressor immediately de-energizes.

•Outdoor fan (if present) de-energizes.

•Fault is indicated (on earlier software versions).

42	McQuay OM 751

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Contents DX Cooling Only Software Model UV05 Group Applied SystemsDate November Getting Started UVC Configuration ParametersIntroduction Description of OperationModel-specific unit ventilator installation literature Accessory-specific installation literatureDescription Manual # Extreme temperature can damage system components Software program literatureAcronyms/Abbreviations Acronyms and abbreviationsDescription Acronym Abr OCS Keypad Functions Using the Keypad/DisplayDisplay Format Security LevelsFAN Key Mode KeyON/STOP Key and LED Arrow KeysMenu Reference Using the Keypad/DisplayViewing Actual Indoor Air Temperature IAT Changing Set PointsAbr Description Default RW1Chlo Description of Operation State ProgrammingComplete UVC-state diagram UVC Unit ModesNormal UVC modes State names OFF Mode StateUVC state names and numbers DecimalNight Purge Mode State Fan Only Mode State aEmergency Heat Mode Super State Full Heat State StateCant Heat State State D Auto Mode Heat Mode Super StateHeat State State Cool Mode Super State Low Limit State State ECant Heat State State B Cool mode super state diagram Econ State StateEcon Mech State State Mech State StateLow Limit State State F Special Purpose Unit ModesDischarge Air DA Heat State State Cant Cool State State CPurge Mode Pressurize ModeDepressurize Mode Shutdown ModeNormal UVC mode priority Unit Mode PrioritySpecial purpose UVC unit mode priority Priority resultStandby Mode Occupied ModeUnoccupied Mode Occupancy mode priorityAdditional Occupancy Features Networked Set Point Capability Space Temperature Set PointsNetworked Space Temperature Sensor Capability Networked Set Point Offset CapabilityRemote Wall-Mounted Sensor with +/-3F Adjustment optional Effective Set Point CalculationsSet point calculation examples Example a Example B GivenEffective set point calculations PI loop list Discharge Air Temperature ControlProportional Integral PI Control Loops PI loopsPI Control Parameters Proportional BandIndoor Air Fan Operation Integral TimeOccupied, Standby, and Bypass Operation Outdoor Air Damper Operation Economizer enable EconomizerOA temp sensor Space humidity CO2 Demand Controlled Ventilation optional Networked Space Humidity Sensor CapabilityNetworked Outdoor Humidity Sensor Capability Networked Space CO2 Sensor CapabilityCompressor Envelope Compressor OperationAshrae Cycle Compressor Cooling LockoutFloating-Point Actuator Auto-Zero, Overdrive and Sync Compressor Minimum On and Off TimersCompressor Start Delay Outdoor Air Fan OperationVentilation Lockout Input Signal Unoccupied Input SignalRemote Shutdown Input Signal External Binary InputsFault Signal Exhaust Interlock Input SignalLights On/Off Signal External Binary OutputsAuxiliary heat start/stop calculation Exhaust Fan ON/OFF SignalAuxiliary Heat Signal Start/Stop CalculationInputs and outputs, software model 05-DX cooling only Expansion boardAlarm and Fault Monitoring Alarm and fault code summaryPriority Fault description Reset Keypad Space Temp Sensor Failure F0 DX Pressure Fault F1Compressor Envelope Fault F2 Discharge Air DX Cooling Low Limit Indication F3Outdoor Temp Sensor Failure F6 Condensate Overflow Indication optional F4Space Coil DX Temp Sensor Failure F5 Discharge Air Temp Sensor Failure F7Troubleshooting Temperature Sensors Troubleshooting Humidity Sensors Temperature versus resistanceCO2 versus voltage table Troubleshooting Carbon Dioxide CO2 SensorsHumidity versus voltage RH % VDC mVUVC configuration parameters OM Configuration Parameter Name Abr Default LUI MenuAbr Default LUI Menu OAD Stroke Time Warranty