Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for WeatherExpert 48N2: Installation instructions Installation instructions Controls, start-up, operation, service, and troubleshooting Installation instructions

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Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 101 page image

101Table 73 — Humidi-MiZer® Service AnalysisPROBLEM CAUSE REMEDYSubcooling Mode Will NotActivateCircuit B compressors unavailable Check alarm history for general cooling mode operation problems.See Table 72.Check for Circuit B compressors locked out.General Cooling Mode problem See Table 72.Humidi-MiZer relative humidity sensornot functioning - RARH, SPRH, or fieldinstalled RH sensorCheck that a relative humidity sensor is connected and that theappropriate sensor is configured in the unit software, (Configura-tionIAQDEHUD.SEN). See page 87.Check for 24VDC from CEM (RARH, SPRH).Check 4-20 mA signal from sensor.Humidi-MiZer temperature sensors notfunctioning - SAT, CCTSee "Thermistor Troubleshooting," see page 99.No Dehumidification demand See “No Dehumidification Demand”, below.3-way valve malfunction See “3-Way valve malfunction,” below.Unit control software is not configuredfor Humidi-MiZer systemCheck that the unit is configured for Humidi-MiZer (Configura-tionIAQDEHUD.SEL).Reheat Mode Will Not ActivateCircuit B compressors unavailable Check alarm history for general cooling mode operation problems.See Table 72.Check for Circuit B compressors locked out.Humidi-MiZer relative humidity sensornot functioning - RARH, SPRH, or fieldinstalled RH sensorCheck that a relative humidity sensor is connected and that theappropriate sensor is configured in the unit software, (Configura-tionIAQDEHUD.SEN). See page 87.Check for 24 VDC from CEM (RARH, SPRH).Check 4-20 mA signal from sensor.No Dehumidification demand See "No Dehumidification Demand,” below.3-way valve malfunction See "3-Way Valve Malfunction."Unit control software is not configuredfor Humidi-MiZer systemCheck that the unit is configured for Humidi-MiZer (ConfigurationIAQDEHUD.SEL).No Dehumidification DemandRelative Humidity set point is too low -discrete input (Humidistat, Thermidi-stat, etc.)Check/reduce setting on discrete humidity input device.Relative Humidity set point is too low -RH sensorCheck the dehumidification relative humidity trip point (Configura-tionIAQDEHUD.RH.S)Software configuration error for thetype of relative humidity sensor beingusedCheck that the unit software is configured for the correct relativehumidity sensor (ConfigurationIAQDEHUD.SEN).D.SEN = 1: RARH, 2:SPRH, 3: Discrete Input. See page 87.No humidity signal Check wiring and sensor.3-Way Valve MalfunctionNo 24V signal to input terminals Check using Service Test mode.Check wiring.Check transformer and circuit breakers.Check RCB relay output.Solenoid coil burnout Check continuous over-voltage is less than 10%.Check continuous under-voltage is less than 15%.Check for missing coil assembly parts.Replace solenoid coil.Stuck valve Replace valve. Replace filter drier.Unit Initiates a Humidi-MizerReheat Mode, but Supply AirTemperature is Overheating/Overcooling the SpaceHumid-MiZer Vent Reheat Set Point istoo lowCheck the Vent Reheat Set Point Selection (ConfigurationIAQDEHUD.V.CF) and Vent Reheat Setpoint (Configura-tionIAQDEHU D.V.HT). If used, check the Vent ReheatRAT Offset also (ConfigurationIAQDEHUD.V.RA). Seepage 87 for Humid-Mizer controls set-up.Evaporator discharge temperature(CCT) or supply air temperature (SAT)thermistor is reading incorrectly.See "Thermistor Troubleshooting,” page 99.Check if SAT thermistor is in a location that is measuring stratifiedairValve controlling gas bypass aroundthe condenser is not functioningproperlySee "Modulating Valves Not Functioning Properly"Valve controlling refrigerant flow to thecondenser is not functioning properly See "Modulating Valves Not Functioning Properly"Modulating valves are not calibratedproperly Run valve calibration through Service TestUnit control software indicates aHumidi-MiZer Reheat Mode, but the 3-way valve is not functioning properlySee "3-Way Valve Malfunction"Unit is not sized to meet the load at thecurrent entering air and outdoorconditions.Check product data tables or ECAT for rated capacity at currententering air and outdoor conditions.