Lennox International Inc 4HP18LT manual Thermostat Demand Wiring, Miswired Module Codes

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Thermostat Demand Wiring

The diagnostic module requires a thermostat demand signal to operate properly. The thermostat demand signal input, labeled Y on the module, should always be connected to the compressor contactor coil so that when the coil is energized, the demand signal input is 24VAC. When the coil is not energized, the demand signal input should be less than 0.5VAC.

Miswired Module Codes

Depending on the system configuration, some ALERT flash codes may not be active. The presence of safety switches affects how the system alerts are displayed by the module.

Miswiring the diagnostic nodule will cause false LED codes. Table 12 Describes LED operation when the module is miswired and what troubleshooting action is required to correct the problem.

Miswired Module Troubleshooting

Table 12

506470-01

Issue 1007

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Contents Save these instructions for future reference Lennox International Inc. CompanyGeneral InstallationInstallation Clearances Torque TableSlab Mounting Electrical WiringSlab Mounting Roof MountingInstalling Refrigerant Line Refrigerant PipingLine Set Isolation PlacementOutside Unit Placement & Installation Refrigerant Line Set DiametersRefrigerant Line Sets Installing Horizontal Runs Refrigerant Line Sets Transition from Vertical to Horizontal Flushing Procedure Required EuipmentRefrigerant Metering Device Expansion Valve SystemsTo Access the Schrader Port To Close Liquid or Suction Line Service ValveUsing an Electronic Leak Detector EvacuationIssue START-UP Refrigerant Charge AdjustmentRefrigerant Charging Issue R410A Temperature/Pressure Chart Approach Values for TXV Systems Issue Operation Time Delay Defrost Control Timing PinsCompressor Delay Pressure Switch CircuitInterpreting the Diagnostic LEDs System Diagnostic ModuleLED Description 24VAC Power Wiring Thermostat Demand Wiring Miswired Module CodesMaintenance Temperature Setting Levers Inspect and clean outdoor coilHomeowner Information Temperature Indicator Fan SwitchSystem Switch Indicating LightStart-Up and Performance Checklist Wire Diagram Issue