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 41 page image

41NOTE: If D.F.ON is configured below DAQ.H, the unit is inoccupied mode, and the fan was off, then DAQ rose aboveD.F.ON and the fan came on, the economizer will go to theeconomizer minimum position (EC.MN).The 4 to 20 mA signal from the sensor wired to TB201-8and TB201-7 is scaled to an equivalent indoor CO2 (IAQ) bythe parameters IQ.R.L and IQ.R.H located under the Configu-rationIAQAQ.SR menu. The parameters are defined suchthat 4 mA = IQ.R.L and 20 mA = IQ.R.H. When the differen-tial air quality DAQ (IAQ – OAQ.U) exceeds the DAQ.H setpoint (ConfigurationIAQAQ.SP menu) and the supplyfan is on, the economizer minimum vent position (Configura-tionIAQDCV.CEC.MN) is overridden and the damperis moved to the IQ.P.O configuration. When the DAQ falls be-low the DAQ.L set point (ConfigurationIAQAQ.SPmenu), the economizer damper is moved back to the minimumvent position (EC.MN).NOTE: Configuration OAQ.U is used in the calculation of thetrip point for override and can be found under Configura-tion IAQAQ.SP.IQ.A.C = 3 (4 to 20 mA Damper Control) — This configura-tion will provide full 4 to 20 mA remotely controlled analog in-put for economizer minimum damper position. The 4 to 20 mAsignal is connected to terminals TB201-8 and TB201-7. Theinput is processed as 4 mA = 0% and 20 mA = 100%, therebygiving complete range control of the effective minimumposition.The economizer sequences can be disabled by unplugingthe enthalpy switch input and not enabling any other econo-mizer changeover sequence at Configura-tionECONE.SEL. Complete control of the economizerdamper position is then possible by using a 4 to 20 mA econo-mizer minimum position control or a 0 to 10,000-ohm 0 to100% economizer minimum position control via configurationdecisions at ConfigurationIAQAQ.CFIQ.A.C.To disable the standard enthalpy control input function,unplug the enthalpy switch and provide a jumper from TB201-6 to TB201-5 (see wiring diagrams in Major System Compo-nents section on page 127).IQ.A.C = 4 (10,000 ohm Potentiometer Damper Control)— This configuration will provide input for a 10,000 ohm lin-ear potentiometer that acts as a remotely controlled analog in-put for economizer minimum damper position. The input isprocessed as 0 ohms = 0% and 10,000 ohms = 100%, therebygiving complete range control of the effective minimumposition.NOTE: For complete economizer control, the user can makethe economizer inactive by unplugging the enthalpy switchconnection.CONTROLS OPERATIONModes — The ComfortLink controls operate under a hierar-chy of command structure as defined by three essential ele-ments: the System mode, the HVAC mode and the Controlmode. The System mode is the top level mode that defines threeessential states for the control system: OFF, RUN and TEST.The HVAC mode is the functional level underneath theSystem mode which further defines the operation of thecontrol.The Control mode is essentially the control type of the unit(ConfigurationUNITC.TYP). This defines from wherethe control looks to establish a cooling or heating mode.Furthermore, there are a number of modes which operateconcurrently when the unit is running. The operating modes ofthe control are located at the local displays under OperatingModes. See Table 24.Currently Occupied (OCC) — This variable displays the cur-rent occupancy state of the unit.Timed Override in Effect (T.OVR) — This variable displaysif the state of occupancy is currently occupied due to anoverride.DCV Resetting Minimum Position (DCV) — This variabledisplays if the economizer position has been lowered from itsmaximum vent position due to demand control ventilation.Supply Air Reset (SA.R) — This variable displays if the sup-ply air set point that the rooftop is attempting to maintain iscurrently being reset upwards. This applies to cooling only.Table 24 — Operating Modes Display TableDemand Limit in Effect (DMD.L) — This variable displaysif the mechanical cooling capacity is currently being limited orreduced by a third party.Temperature Compensated Start (T.C.ST) — This variabledisplays if Heating or Cooling has been initiated before occu-pancy to pre-condition the space.IAQ Pre-Occupancy Purge Active (IAQ.P) — This variabledisplays if the economizer is open and the fan is on to pre-ventilate the building before occupancy.Linkage Active CCN (LINK) — This variable displays if alinkage master in a zoning system has established “linkage”with this air source (rooftop).Mechanical Cooling Locked Out (LOCK) — This variabledisplays if mechanical cooling is currently being locked outdue to low outside air temperature.HVAC Mode Numerical Form (H.NUM) — This is a numer-ical representation of the HVAC modes which may be read viaa point read.SYSTEM MODES (Operating ModesSYS.M)System Mode Off — When the system mode is OFF, all out-puts are to be shut down and no machine control is possible.The following list displays the text assigned to the SystemMode when in the OFF mode and the conditions that maycause this mode are checked in the following hierarchal order:1. Wake up timer on a power reset.(“Initializing System ...”)2. System in the process of shutting down compressors andwaiting for timeguards to expire.(“Shutting Down ...”)3. Factory shut down (internal factory control level —SHUTDOWN).(“Factory Shut Down”)4. Unit Stop (software application level variable that acts asa hard shut down — Service TestSTOP).(“Local Machine Stop”)5. Fire Shut Down (fire shutdown condition based on theFire Shutdown Input (InputsFIREFSD).(“Fire-Shutdown Mode”)ITEM EXPANSION RANGE CCN POINTSYS.M ascii string n/aHVAC ascii string n/aCTRL ascii string n/aMODE MODES CONTROLLING UNITOCC Currently Occupied ON/OFF MODEOCCPT.OVR Timed Override in Effect ON/OFF MODETOVRDCV DCV Resetting Min Pos ON/OFF MODEADCVSA.R Supply Air Reset ON/OFF MODESARSDMD.L Demand Limit in Effect ON/OFF MODEDMLTT.C.ST Temp.Compensated Start ON/OFF MODETCSTIAQ.P IAQ Pre-Occ Purge Active ON/OFF MODEIQPGLINK Linkage Active — CCN ON/OFF MODELINKLOCK Mech.Cooling Locked Out ON/OFF MODELOCKH.NUM HVAC Mode Numerical Form number MODEHVAC