American Standard UV05 manual Troubleshooting Humidity Sensors, Temperature versus resistance

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Diagnostics and Service

3Use the temperature reading from Step 2 to determine the expected sensor resistance from Table 23.

4Using a calibrated ohmmeter, measure the actual resistance across the two sensor leads.

5Compare the expected resistance to the actual resistance.

6If the actual resistance value deviates substantially (more than 10%) from the expected resistance, replace the sensor.

Table 23: Temperature versus resistance

°F (°C)	Resistance in ohms	°F (°C)	Resistance in ohms
–40 (–40)	613	113 (45)	1195
–31 (–35)	640	122 (50)	1237
–22 (–30)	668	131 (55)	1279
–13 (–25)	697	140 (60)	1323
–4 (–20)	727	149 (65)	1368
5 (–15)	758	158 (70)	1413
14 (–10)	789	167 (75)	1459
23 (–5)	822	176 (80)	1506
32 (0)	855	185 (85)	1554
41 (5)	889	194 (90)	1602
50 (10)	924	203 (95)	1652
59 (15)	960	212 (100)	1702
68 (20)	997	221 (105)	1753
77 (25)	1035	230 (110)	1804
86 (30)	1074	239 (115)	1856
95 (35)	1113	248 (120)	1908
104 (40)	1153

Troubleshooting Humidity Sensors

The UVC is configured to use a 0–100% RH, 0–5 VDC, capacitive humidity sensor. Each sensor is calibrated according to the table shown.

CAUTION

The humidity sensor is not protected against reversed polarity. Check carefully when connecting the device or damage can result.

Use the following procedure to troubleshoot a suspect sensor:

1Disconnect the sensors output voltage lead from the UVC analog input.

2Using some other calibrated humidity sensing device, take a humidity reading at the sensor location.

3Use the humidity reading from Step 2 determine the expected sensor voltage from Table 24.

4Using a calibrated multi-meter, measure the actual voltage across the yellow and white sensor leads.

Wire color definitions: White = ground Yellow = output VDC Blue = supply VDC

5Compare the expected voltage to the actual voltage.

6If the actual voltage value deviates substantially (more than 10%) from the expected voltage, replace the sensor.

McQuay OM 751

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Contents DX Cooling Only Software Model UV05 Group Applied SystemsDate November Introduction UVC Configuration ParametersGetting Started Description of OperationModel-specific unit ventilator installation literature Accessory-specific installation literatureDescription Manual # Software program literature Extreme temperature can damage system componentsAcronyms/Abbreviations Acronyms and abbreviationsDescription Acronym Abr OCS Display Format Using the Keypad/DisplayKeypad Functions Security LevelsON/STOP Key and LED Mode KeyFAN Key Arrow KeysViewing Actual Indoor Air Temperature IAT Using the Keypad/DisplayMenu Reference Changing Set PointsRW1 Abr Description DefaultChlo State Programming Description of OperationUVC Unit Modes Complete UVC-state diagramUVC state names and numbers OFF Mode StateNormal UVC modes State names DecimalFan Only Mode State a Night Purge Mode StateEmergency 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 Econ State State Cool mode super state diagramMech State State Econ Mech State StateDischarge Air DA Heat State State Special Purpose Unit ModesLow Limit State State F Cant Cool State State CDepressurize Mode Pressurize ModePurge Mode Shutdown ModeSpecial purpose UVC unit mode priority Unit Mode PriorityNormal UVC mode priority Priority resultUnoccupied Mode Occupied ModeStandby Mode Occupancy mode priorityAdditional Occupancy Features Networked Space Temperature Sensor Capability Space Temperature Set PointsNetworked Set Point Capability Networked Set Point Offset CapabilityEffective Set Point Calculations Remote Wall-Mounted Sensor with +/-3F Adjustment optionalSet point calculation examples Example a Example B GivenEffective set point calculations Proportional Integral PI Control Loops Discharge Air Temperature ControlPI loop list PI loopsProportional Band PI Control ParametersIndoor Air Fan Operation Integral TimeOccupied, Standby, and Bypass Operation Outdoor Air Damper Operation Economizer enable EconomizerOA temp sensor Space humidity Networked Outdoor Humidity Sensor Capability Networked Space Humidity Sensor CapabilityCO2 Demand Controlled Ventilation optional Networked Space CO2 Sensor CapabilityAshrae Cycle Compressor OperationCompressor Envelope Compressor Cooling LockoutCompressor Start Delay Compressor Minimum On and Off TimersFloating-Point Actuator Auto-Zero, Overdrive and Sync Outdoor Air Fan OperationRemote Shutdown Input Signal Unoccupied Input SignalVentilation Lockout Input Signal External Binary InputsLights On/Off Signal Exhaust Interlock Input SignalFault Signal External Binary OutputsAuxiliary Heat Signal Exhaust Fan ON/OFF SignalAuxiliary heat start/stop calculation Start/Stop CalculationExpansion board Inputs and outputs, software model 05-DX cooling onlyAlarm and Fault Monitoring Alarm and fault code summaryPriority Fault description Reset Keypad Compressor Envelope Fault F2 DX Pressure Fault F1Space Temp Sensor Failure F0 Discharge Air DX Cooling Low Limit Indication F3Space Coil DX Temp Sensor Failure F5 Condensate Overflow Indication optional F4Outdoor Temp Sensor Failure F6 Discharge Air Temp Sensor Failure F7Troubleshooting Temperature Sensors Temperature versus resistance Troubleshooting Humidity SensorsHumidity versus voltage Troubleshooting Carbon Dioxide CO2 SensorsCO2 versus voltage table RH % VDC mVConfiguration Parameter Name Abr Default LUI Menu UVC configuration parameters OMAbr Default LUI Menu OAD Stroke Time Warranty