LETCO ENTERPRISES PRESENTS - MACS …

1 LETCO ENTERPRISES PRESENTSNAVISTAR HVAC SYSTEMS OVERVIEW AND SERVICES TIPSNAVISTAR MODELSLONESTARPROSTARNAVISTAR MODELSDURASTARTRANSTARMULTIPLEXED ELECTRICAL SYSTEM Electrical devices outputs; lamps, gauges, switches controlled by an ECU Use data links to send multiple signals to ECUs System can both: a. Perform tasks, b. Monitor components Communication by Datalinks: decreases total number of wires required. By connecting switches to ECUs, the ECUs can then share switch information on the Datalink with other Computers talk in Binary code uses 8 Bits to make a Byte, 8 Bit Binary Alphabet 1248163264128 Uses a base system of 2: 0 = low voltage: Off, Low, No 1= High voltage: On, High, Yes Example of Binary Message: 191 2 4 8 16 32 64 1281 1 0 0 1 0 0 05 NAVISTAR ELECTRONIC ARCHITECTUREM ainly Engine StuffView Faults and Programming9600 KNo Terminating ResistorsNAVISTAR ELECTRONIC ARCHITECTUREJ1939 Drivetrain Data Link250 KTerminating Resistors(2) 120 Ohm1.

2 Instrument Panel Opposite to Fuse block center2. Located on Transmission HarnessJ1939 BUS ISSUES Loss of Power, Ignition or Ground to a Module will set communication Faults. Low Battery voltage can cause voltage shedding that may turn off a module. Always confirm Power and Grounds and Charging System before J1939 BUS ISSUES Open Backbone: loss of terminating resistor, loose or disconnected bus leg. DTCs will set that messages from modules below the break have not been received. Open or Loose connection to an single module: Only the affected Module will not report. Other modules will set DTC indicating that the dead module messages were not received. Short: any short to ground or short to voltage or CAN High or CAN Low shorted together will result in no communication between the modules or data line.

3 DSL CONNECTORDATA LINK CIRCUIT TESTSNAVISTAR HVAC SYSTEMS CCOT 2001 thru March 2007 TXV March 2007 and UpCompressorCondenserAccumulatorEvaporat orOrifice TubeExpansion ValveExpansion ValveCompressorCompressorCondenserConden serReceiver/DrierReceiver/DrierEvaporato rEvaporatorCOMMON HARDWAREE lectronic Gauge ClusterHVAC Control Head (RCD) Refrigerant Control and Diagnostic System Sets Fault Codes and turns on the CHECK A/C warning lamp. Control grounds A/C Request signal at Body Module Sends Diagnostic Signal to the Body HARDWAREE lectrical System ControllerHVAC Control Head Sees A/C Request from Control Head Less then .8 DC v. Receives Control Head Diagnostic SignalMonitors some conditions and notifies the ESCwhen it detects a HARDWAREBody ModuleECM Engine RPM to Body Module via J1939 Drivetrain Data Line Vehicle Speed to Body Module via J1939 Drivetrain Data link.

4 Aux HVAC Controls talk on the J1939 Body Data ESC/BCM will assign a DTC s to each faultA Fault that sets onetime is stored as inactive in the EGC the fault repeats, it is Active and stored in the HARDWAREE ngine Control ModulePower Distribution CenterControls Engine Fan SolenoidMonitors Engine RPMC ontains the Main power fuses for subsystemsFuse element may crack and cause intermittent power loseCOMMON HARDWAREP ressure TransducerAir Driven Engine Fan If Equipped Works like a Binary and Fan Switch in One. Communicates on the J1939 drivetrain data Linkbetween the Body Module and the ECM. Turns On 285 PSI and Higher,Runs at one minute intervalsuntil head pressure is below 185 PSIFan will turn on when A/C Request signal is received and Vehicle speed is less then 10 MPH, engine speed over 1200 RPM,High Side Pressure over 100 PSI and Inlet Thermistor over 85 CLUTCH VOLTAGE FLOW TWO THERMISTORSA/C RequestBody ControllerModuleA/C DiagnosticsEvap Outlet ThermistorEvap Inlet ThermistorA/C Pressure TransducerFeedA/C Pressure Transducer SignalA/C Compressor A/C Pressure Transducer Thermistor SignalInletThermistorOutletThermistorZVR FET ControlledCLUTCH ENGAGEMENT RULES TWO THERMISTORS Engine RPM at 300 RPM minimum at BC for at least 8 Seconds The A/C request from the HVAC control head must be less then.

5 8 V dc. Blower motor ON. Pressure Transducer Pressure between 40 and 250 PSI. Outlet Thermistor above 33 F. Inlet Thermistor above 43 F. No Active Thermistor DTCs Control Head Diagnostic signal must be present . No Clutch Circuit FET DTC s and Clutch Draw less then 10 HARDWARET hermistorsPressure Transducer Inlet Thermistor: 30 F to 43 F Outlet Thermistor: Below 24 F Clutch on for more then 7 Seconds Turns Off Clutch Less then 250 PSI Above 40 PSI. Outlet Thermistor Above 33 F. Turn A/C Clutch Off if high side over 400 RESISTANCE TESTSCOMPARE READINGS WITH CHARTUSE IN INFRARED THERMOMETER AND COMPARE LINE TEMPERATURE TO GAUGE PRESSURE READINGPRESSURE TRANSDUCER TESTS Back probe Pin B12 to Ground and Compare Voltage to Pressure ReadingPressureTransducerControlHeadA/CC lutchA/C CLUTCH VOLTAGE FLOW FREEZE PROBEA/C RequestBody ControllerModuleA/C DiagnosticsEvap Outlet ThermistorEvap Inlet PressureA/C Pressure TransducerFeedA/C Pressure Transducer SignalA/C Compressor A/C Pressure Transducer Thermistor SignalFin ProbeThermistorZVRLow Pressure SwitchCLUTCH ENGAGEMENT RULES FREEZE PROBE Engine RPM at 300 RPM minimum at BC for at least 8 Seconds The A/C request from the HVAC control head must be less then.

6 8 V dc. Blower motor ON. Pressure Transducer Pressure between 40 and 250 PSI. Freeze Probe Above 32 F. Low Pressure Switch Closed. No Active Thermistor DTCs Control Head Diagnostic signal must be present . No Clutch Circuit FET DTC s and Clutch Draw less then 10 HARDWAREFin ProbeESC/Body ModuleBe Sure to Note the Depth of the Probe Before Removal. Position New Probe to Same DepthElectrical System Controller is the main Processor of the multiplexing PROBE TESTING Back probe connector at Plenum InletTXV HARDWARELow Pressure SwitchPressure TransducerTXV HARDWARE LOW PRESSURE SWITCH TESTS Ignition OFF Disconnect Switch Connector from Switch Check Continuity Between Pin J and K circuit complete Ignition ON check Pin J to Ground. Voltage 10 volts or Higher, if less then 10 Volts Check Connector B5 at ESC, If voltage is 10 Volts or Higher If B5 Volts OK, check connector pins for damage at ESC and Switch connectorCOMMON HARDWARECoil Resistance: Ohms OhmsMaximum Current: AMPSC lamping Diode in The Field CoilReplacement Compressor has Full Oil Charge: Type: SP-15 Clutch Armature Air Gap: FAILURE Damaged Reed Valves: Caused by Flooding Evaporator Due to TXV Problems.

7 Damaged Reed Valves; Caused by Liquid ChargingCLUTCH FAILURE Common Clutch Problems External Oil Leaks Position of Snap Rings Clutch Hub Air Gap Charging System Voltage Drops Ground Circuit Air Flow Internal RestrictionsCOMMON HARDWAREB lower MotorLinear Power ModuleCOMMON HARDWAREC ondenserEngine FanCan be Flushed per IHCOil Capacity: ouncesFitting Torque: 14-15 Ft Applications will use a Viscous Fan ClutchCOMMON HARDWAREI nputs for A/C and Engine Fan4 wire design on late Models moved to Discharge :Missing 5 Volt PT reference will cause Air Pressure gauges to read incorrectly! Pressure TransducerAmbient Temperature SensorRange -40 F - 176 FWill display ICE at 38 FMounted by DS frame rail below door areaBehind Front License Plate bracket Late HARDWAREE vaporator Heater CoreVehicle May be Equipped with Shut Off Capacity: Be FlushedC-plate Nuts: 14 15 Ft LbsCOMMON HARDWAREB lock FittingsC- Plate and O-ringwith Flanged Nut C-Plate Fittings are a Combinationof Sealing Washer and O ringTorque to: 14-15 Ft LbsCompressor Mounting Bolts.

8 17-21 Ft Lbs C-Plate Installed Dry, O ring Lubed withMineral use a Flange Nut Torque 14-15 Ft LbsCOMMON HARDWARECab Filter Access ProStarCab Filter Access DuraStarCOMMON HARDWARER ecirculation Filter LHRecirculation Filter RHAIR MANAGEMENTC ontrol Head Design and Operation Similar across all platformsAIR MANAGEMENT COMPONENTSC ontrol Head connector can beDisconnected to Recal HVACEGC: electronic Gauge ClusterWill display A/C warning Message and DTC sAIR MANAGEMENT COMPONENTSMain Fuse PanelESC: Electronic System ControllerESC/BODY CONTROLLER Monitors HVAC Parameters Sets DTCs when parameter is out of range. If system damage can occur the ESC/Body Controller will disable the compressor. TIP: Quick Check for Ground to BC, Done light will work with Key On or Off.

9 With Key Off open Door, If the Dome light does not turn on the BC may have lost its ground. Quick Check for Voltage, With Key On, turn on the wipers, If the wipers do not work, the BC may have lost ignition or Accessory power. If the wipers work, the BC Has correct CONTROLLERESCD igital InputsAnalog InputsSwitch Data LinkOutputsBody Data LinkDrivetrain Data LinkDoorBrakeTurn SignalA/C TemperatureA/C PressureAir Pressure Primaryand SecondaryA/C RequestJ1708 Center Panel SwitchesDoor PodsA/C ClutchDome LightsHeadlampsMarker LightsTurn LampsStop LampsJ1939 RPMASMRESCMJ1939 ECMTCMABSEGCBLOWER MOTOR AND LPMP ermanent Magnet Design Linear Power Module Seven Blower Speeds, Reads the Control Panel Output of 0 to Volts. The LPM acts as a variable resistor between the Blower Motor and MOTOR LINEAR POWER MODULE (LPM)Either Located on side of Evaporator Case Or on Blower Square or Horseshoe ShapedCONTROL HEAD TESTING Disconnect Connector from LPM measure voltage on the three wire connector between Pin 4 and 5.

10 If Voltage readings are out of Specs, Replace Control Head. BLOWER MOTOR TESTING Disconnect the two wire LPM Connection. Measure Voltage between the Red and Black Wire. If Voltage Readings Matchtest chart: Replace Blower Motor If Voltage Readings Do Not Match test chart, Replace Linear Power MANAGEMENT ACTUATORSR ecirculation DoorActuatorMode Door ActuatorBlend DoorActuatorACTUATOR MOTOR PRECAUTIONS To Prevent Actuator Damage never force the drive collar into position. Place the door actuator in the approximate position Connect a 9 Volt Battery to the correct pins on the motor. Switch Battery leads to turn motor in the opposite direction. Rotate until the collar is aligned with the door shaft Torque mounting screws to: 20 inch pounds. Calibrate the DOOR ACTUATORB lend Door Motor and Gear Train MODE DOOR GEAR TRAINRECIRCULATION GEAR TRAINHVAC ACTUATOR CALIBRATIONFuse Panel Fuse /Relay ChartHVAC ACTUATOR CALIBRATIONACTUATOR RECALIBRATION Engine Off Key On Blower ON Mode Selector to Defrost Mode Remove the Fuse F1-B 5 Amp HVAC Control Head Wait 30 Seconds and then reinstall fuse.