Lennox International Inc MERIT SERIES GAS FURNACE DOWNFLOW AIR DISCHARGE, ML193DF

Page 47

Troubleshooting: Cooling Sequence of Operation

COOLING SEQUENCE OF OPERATION

NORMAL COOLING MODE

 

 

ABNORMAL COOLING MODE

 

 

 

 

 

 

 

 

 

 

 

 

POWER ON

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IGNITION CONTROL MAIN POWER ON.

 

 

 

 

 

 

 

 

 

 

NO

 

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

 

CONTROL SELF DIAGNOSTIC CHECK.

 

INDOOR BLOWER OFF WITH NORMAL DELAY.

 

IS CONTROL OPERATING NORMALLY?

 

 

SIGNAL CIRCUIT BOARD FAILURE AT LED.

 

 

 

YES

 

 

 

 

INTERRUPT MAIN POWER TO RESET CONTROL.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SIGNAL IMPROPER GROUND AT LED.

 

IS THERE A PROPER GROUND?

 

 

CONTROL WILL CONTINUE TO CALL FOR COOLING

 

 

 

YES

 

 

 

 

IN THIS CONDITION.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

SIGNAL POLARITY REVERSED AT LED. CONTROL

 

 

 

 

 

 

 

 

 

IS POLARITY CORRECT?

 

 

WILL CONTINUE TO CALL FOR COOLING IN THIS

 

 

 

 

 

 

 

 

CONDITION.

 

 

 

YES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

 

 

 

 

 

 

IS VOLTAGE

 

 

 

LED SIGNALS LOW VOLTAGE. CONTROL WILL

 

 

 

 

 

 

 

 

 

ABOVE 90 VOLTS?

 

 

 

CONTINUE TO CALL FOR COOLING

 

 

 

 

 

 

 

 

 

YES

 

 

 

 

IN THIS CONDITION.

 

 

 

 

 

 

 

 

 

 

 

 

 

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

INDOOR BLOWER ON.

ROLLOUT SWITCH MONITORED CONTINUOUSLY.

 

 

SIGNAL ROLL-OUT SWITCH OPEN AT LED.

IS ROLLOUT SWITCH CLOSED?

 

 

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES

 

 

 

 

 

 

 

AND MAIN POWER IS INTERRUPTED OR THERMOSTAT

 

 

YES

 

 

 

 

IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LED: SLOW FLASH RATE REMAINS UNCHANGED

THROUGHOUT COOLING CYCLE.

THERMOSTAT CALLS FOR COOLING.

COMPRESSOR CONTACTOR AND SYSTEM FAN

ENERGIZED WITH 2-SECOND DELAY

(COOLING SPEED). EAC TERM. ENERGIZED.

THERMOSTAT OPENS.

COMPRESSOR OFF.

SYSTEM FAN AND EAC TERM. OFF

WITH 45-SECOND DELAY.

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Contents Table of Contents Installation Instructions ML193DFML193DF ML193DF Unit Dimensions − inches mmBlower Motor BAG AssemblyML193DF Parts Arrangement Control BOXShipping and Packing List Safety InformationDirect Vent Installation NON−DIRECT Vent ML193DF Gas FurnaceUse of Furnace as Construction Heater Combustion, Dilution & Ventilation Air GeneralEquipment in Confined Space − ALL AIR from Inside Equipment in Confined Space − ALL AIR from Outside Shipping Bolt RemovalFront Horizontal Back Installation − Setting EquipmentSetting Equipment NC‡ NON−COMBUSTIBLE Floor Opening Size− Seal the cabinet and check for air leaks Combustible Flooring Base Opening SizeSide View Duct System Pipe & Fittings SpecificationsPiping and Fittings Specifications FiltersOutdoor Termination Kits Usage Schedule Joint Cementing ProcedureVenting Practices Piping Suspension GuidelinesML193DF MIN. Vent Length Model Vent Piping GuidelinesMinimum Vent Pipe Lengths Maximum Allowable Intake or Exhaust Vent Length in Feet Intake Exhaust Typical Exhaust Pipe ConnectionsTypical Intake Pipe Connections Typical AIR Intake Pipe Connections Inches 305mm or 12 in mm Inside Corner DetailUS Installations1 Canadian Installations2 FLUSH−MOUNT Side Wall Termination KIT 51W11 − On field supplied terminations, a minimum distanceDirect Vent Roof Termination KIT 51mm 76mm Vent Pipe Support Reducer MAY beRequired to Adapt Unconditioned SpaceTop View Front ViewExhaust NON−DIRECT Vent Roof Termination KIT 203mm − 305mmML193DF NON−DIRECT Vent Application Using Existing Chimney To drain ML193DF with Evaporator CoilTrap / Drain Assembly Using 1/2 PVC or 3/4 PVC Furnace Isolate GAS Valve Gas PipingGAS Pipe Capacity − FT3/HR kL/HR Electrostatic Discharge ESD Precautions and ProceduresElectrical BOX Inside FACTORY− Installed Left Side MAKE−UPInterior MAKE−UP BOX Exterior MAKE−UP BOXThermostat Designations Typical ML193DF Field Wiring DiagramTypical ML193DF Wiring Diagram Automatic Hot Surface Ignition System For Your Safety Read Before OperatingUnit Start−Up Integrated ControlPage High Altitude Information Gas Pressure AdjustmentGAS Meter Clocking Chart Proper Combustion73W37 73W81 68W68 74W90 74W91 69W73 2286 − 3038m2286m 3048m No Jumper Other Unit AdjustmentsHeat FAN-OFF Time in Seconds High Low In. w.g Cfm Watts Cfm Watts cfm Watts Blower DataElectrical SHOCK, Fire Or Explosion Hazard ServicePage LED #1 Red LED #2 Green Planned ServiceIgnition Control Board Diagnostic Codes Diagnostic CodesHeating Sequence of Operation Troubleshooting Heating Sequence of OperationNormal Heating Mode Abnormal Heating Mode Heating Sequence Cooling Sequence of Operation Troubleshooting Cooling Sequence of OperationNormal Cooling Mode Abnormal Cooling Mode Continuous Heat Speed FAN Sequence of Operation Troubleshooting Continuous Fan Sequence of OperationRepair Parts List Intake / Exhaust Pipe Start−Up & Performance Check ListGAS Supply Return AIR Duct System Supply AIR DuctVent Pipe Temperature RiseTotal External Static Drain Line Condensate Line ThermostatLY BELOW. Keep Clear of ALL OBSTRUC- Tions Requirements for Commonwealth of Massachusetts
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