Trane ZN.520, Tracer Unit Ventilator Outdoor air damper stays open, Probable Cause Explanation

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Troubleshooting

Table 33: Outdoor air damper stays closed

	Probable cause	Explanation


		You can communicate a desired operating mode (such as OFF, HEAT, and COOL) to the controller. When
	Requested mode OFF	OFF is communicated to the controller, the unit controls the fan OFF. There is no heating or cooling
		(valves are closed).

		When the fan is OFF and the outdoor air temperature is below the freeze avoidance setpoint, the
	Freeze avoidance	controller disables economizing and keeps the outdoor air damper closed. This includes UNOCCUPIED
		mode when there is no call for capacity or any other time the fan is OFF.

	UNOCCUPIED mode	When the controller is in the UNOCCUPIED mode, the outdoor air damper remains closed unless
	UNOCCUPIED mode	economizing is enabled.
		economizing is enabled.

		The controller includes both a morning warm up and cool-down sequence to keep the outdoor air
	Warm up and cool-down	damper closed during the transition from UNOCCUPIED to OCCUPIED. This is an attempt to bring the
		space under control as quickly as possible.

		The controller opens and closes the outdoor air damper based on the controller's occupancy mode and
		fan operation. Normally, the outdoor air damper is open during OCCUPIED, OCCUPIED STANDBY, and
	Normal operation	OCCUPIED BYPASS mode when the fan is running and closed during UNOCCUPIED mode unless the
		controller is economizing. For more information see, Modulating Outdoor Air Operation, on page 43 for
		more information.)

	Table 34: Outdoor air damper stays open

	Probable Cause	Explanation


	Unit wiring	The wiring between the controller outputs and the outdoor air damper must be present and correct for
	Unit wiring	normal damper operation.
		normal damper operation.

		The controller must be properly configured based on the actual installed end devices and application.
	Unit configuration	When the unit configuration does not match the actual end devices, the damper may not work
		correctly.

		The controller includes a manual output test sequence you can use to verify output operation and
	Manual output test	associated output wiring. However, based on the current step in the test sequence, the unit damper
		may be open. For more information see, Manual Output Test, on page 48 for more information.)

		The controller opens and closes the outdoor air damper based on the controller's occupancy mode and
		fan operation. Normally, the outdoor air damper is open during OCCUPIED, OCCUPIED STANDBY, and
	Normal operation	OCCUPIED BYPASS mode when the fan is running and closed during UNOCCUPIED mode unless the
		controller is economizing. For more information see, Modulating Outdoor Air Operation, on page 43 for
		more information.)

UV-SVP01A-EN

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Contents Installation Owner Diagnostics Tracer ZN.520 for Classroom Unit VentilatorStart-up Procedures Installation of New UnitsPower Up Sequence General Information Tracer ZN.520 OverviewGeneral Information Controller Circuit Board Features Tracer ZN.520 unit controller circuit boardService Controller FeaturesTypical Components Peer-to-Peer Communications Communication ConfigurationsIntegrated Comfort System Communication Interface Stand-AloneInteroperability End Device Specifications CharacteristicStandard End Devices DescriptionStandard End Devices Way Control Valve Time clock Zone sensor Dpdt Control Transformer Installation and Wiring SpecificationsBinary Inputs Binary Outputs Generic/baseboard Heat Binary OutputAnalog Inputs Analog inputsMounting Vertical classroom unit ventilator end pocket Wiring PowerInstalling the Wall- Mounted Zone Sensor Optional Proper zone sensor placementHumidity and CO2 Sensors Typical Wiring Diagram-Wall Mounted Zone Sensor Typical Wiring Diagram-Unit Mounted Zone Sensor Typical Wiring Diagram-Unit Input/Output Summary Input and output summaryInput/Output Summary Configuration Configurable parametersCooling source Heating sourceBinary Outputs1 Binary input summary Configuration Binary Inputs1Analog Inputs1 Analog input summaryFan Configuration End Device ConfigurationsFan configuration ranges DefaultSetpoint defaults Default Valid range Discharge air limit ranges Default Valid rangeSetpoints Discharge Air LimitsPower-Up Control Wait Occupied Bypass TimerMaintenance Timers Unit Identification Tag Location IdentifierWinking Power-Up Unit OperationHeating And Cooling Changeover Logic OccupancyHeat/Cool Changeover logic Fan Off Delay Cooling OperationHeating Operation Fan OperationValve Operation Face-and-Bypass Damper OperationExhaust fan/damper operation Modulating ValvesEntering Water Temperature Sampling Water assumption chartUnit Configuration Temperature Assumed1Economizer Operation DX OperationElectric Heat Operation Baseboard Heat OperationFilter Status/ Maintenance Timer Output OverridesFan Status Other ModesData Sharing-LonWorks Simple data sharing applicationMore complex data sharing application Heating And Cooling Changeover Logic Heat/Cool Changeover logic Cooling Operation Valve Operation Entering Water Temperature Sampling Economizer Operation Output Overrides Data Sharing-LonWorks More complex data sharing application Troubleshooting Red Service LEDBlack Service Push Button Yellow Comm LEDTest Procedure Exit6Troubleshooting Space Temperature Failure Entering Water Temperature FailureDischarge Air Temperature Limit Outdoor Air Temperature FailureDiagnostics Troubleshooting Translating Multiple Diagnostics Rover service tool FansValves stay closed Probable cause Possible Explanation ValvesValves stay open Probable cause Possible Explanation Outside Air Damper DX/Electric HeatOutdoor air damper stays closed Probable cause Explanation Outdoor air damper stays open Probable Cause ExplanationTracer ZN.520 Unit Controller Replacement Replacing Circuit BoardsHardwired Setpoint Adjustment Fan Switch Resistance ValuesHardwired Thermistor Values AppendixAppendix-Binary Configuration Binary ConfigurationBinary configuration details Binary input or output FunctionHeat/cool mode input NviHeatCool Effective heat/ cool mode output nvoHeatCoolAppendix-Unit Operation Unit Operation Based On The Effective HEAT/COOL OutputAppendix-Unit Operation Configuration properties1 Appendix-Data ListsData Lists Input/output listing1Setting the Time Clock Appendix-TimeclockSet the Time and Day Set the ProgramReview and Change Programs Override Program Manual OperationAppendix-Timeclock Appendix-Location Identifier Location Identifier Location Identifier Location Identifier Trane Company