QuestionI need to replace the heater core in my 1998 gmc jimmy 4x4, 4.3L, automatic. I understand that it is a big job and I am up for it. Just looking for insite, recomendations, pictures...as my store bought manual isnt sufficient. Please email any help.
Thanks
Answerthese are all the steps involved it is a huge job, best of luck i can give pictures there are a lot so if you get stuck let me know and i will try to post them
•Removal Procedure
•Remove the instrument panel. Refer to Instrument Panel Carrier Replacement in Instrument Panel, Gauges and Console.
•Drain the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
•On vehicles with automatic climate control only, cut (1) the outer layer of the A/C evaporator and blower module in order to access the service access cover. Refer to Blower Motor and Fan Replacement .
•On vehicles with automatic climate control only, remove the service access cover mounting screws.
•On vehicles with automatic climate control only, remove the service access cover.
•On vehicles without automatic climate control, remove the blower motor resistor. Refer to Blower Motor Resistor Replacement .
Important: Mark and use the same mounting bolt (located behind the A/C evaporator and blower module) for the heater assembly during the installation process. Other mounting bolts are longer and will obstruct the operation of the temperature door.
•Remove the heat/vent module mounting bolt through the blower motor resistor or service access cover opening.
•On vehicles with A/C only, remove the right wheel house panel. Refer to Wheelhouse Panel Replacement in Body Front End.
•On vehicles with A/C only, raise and support vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
•On vehicles with A/C only, remove the front right tire. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
•On the Utility only, remove the A/C evaporator and blower module heat shield screws.
•On the Utility only, slide the A/C evaporator and blower module heat shield toward the front of the vehicle.
•Remove the 2 lower heat/vent module mounting nuts.
•On the Utility only, remove the A/C evaporator and blower module heat shield bracket.
•Remove the bottom right heat/vent module mounting bolt from inside the vehicle.
Important: The heat/vent mounting stud has a flange on the inside and cannot be removed from under the hood. Stop turning the stud after the threads are off the heat/vent module.
•On the Utility only, while an assistant inside the vehicle pulls the bottom right corner of the heat/vent module approximately 1 inch back, remove the 2 heat/vent module mounting studs.
•On vehicles with A/C only, lower the vehicle.
•On vehicles with a 2.2L engine only, remove the engine wiring harness bracket located at the rear of the intake manifold. Refer to Valve Rocker Arm Cover Replacement in Engine Mechanical - 2.2L.
•Remove the heat/vent module mounting bolt located at the lower left side of the heater core to heater hose connection.
•Remove the heat/vent module mounting nut located at the lower right side of the heater core to heater connection.
Important: The heat/vent mounting stud has a flange on the inside and cannot be removed from under the hood. Stop turning the stud after the threads are off the heat/vent module.
•On the Utility only, loosen the heat/vent module mounting studs until the threads are free from the heat/vent module.
•Disconnect all of the electrical connectors from the heat/vent module.
•Disconnect all of the vacuum lines from the heater assembly.
•Disconnect the heater hoses from the heater core.
•Remove the heat/vent module from the vehicle.
Installation Procedure
•If replacing the heat/vent module, transfer the components from the old heat/vent module as necessary.
Important: Before installing the heat/vent module to the vehicle, ensure that the heat/vent module mounting studs are located in the proper positions.
•Install the heat/vent module to the vehicle.
•Connect the heater hoses to the heater core.
•Connect all of the vacuum lines to the heater assembly.
•Connect all of the electrical connectors to the heat/vent module.
•Install the bottom right heat/vent module mounting bolt from inside the vehicle approximately halfway into the threads.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
•On the Utility only, install the heat/vent module mounting stud located at the lower right side of the heater core to heater hoses connection in the engine compartment.
Tighten
Tighten the heat/vent module mounting stud to 4.5 N·m (22 lb in).
•On vehicles with A/C only, raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
•On the Utility only, install the bottom right heat/vent mounting studs. Ask an assistant to pull the bottom right corner of the heat/vent module back from inside the vehicle.
Tighten
Tighten the heat/vent module mounting studs to 4.5 N·m (22 lb in).
•On the Utility only, install the A/C evaporator and blower module heat shield bracket.
•Install the heater/vent module mounting nuts.
Tighten
Tighten the heat/vent module mounting nuts to 4.5 N·m (22 lb in).
•On the Utility only, slide the A/C evaporator and blower module heat shield into the original position.
•On the Utility only, install the A/C evaporator and blower module heat shield screws.
Tighten
Tighten the A/C evaporator and blower module heat shield screws 2.2 N·m (19 lb in).
•On vehicles with A/C only, install the right front tire. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
•On vehicles with A/C only, lower the vehicle.
•Install the bottom right heat/vent module mounting bolt from inside the vehicle.
Tighten
Tighten the heat/vent module mounting bolt to 4.5 N·m (22 lb in).
•On vehicles with A/C only, install the right wheel house panel. Refer to Wheelhouse Panel Replacement in Body Front End.
•Install the heat/vent module mounting nut located at the lower right side of the heater core to heater connection.
Tighten
Tighten the heat/vent module mounting nut to 4.5 N·m (22 lb in).
•Install the heat/vent module mounting bolt located at the lower left side of the heater core to heater hose connection.
Tighten
Tighten the heat/vent module mounting bolt to 4.5 N·m (22 lb in).
•On vehicles with the 2.2L engine only, install the engine wiring harness bracket located at the rear of the intake manifold. Refer to Valve Rocker Arm Cover Replacement in Engine Mechanical - 2.2L.
Important: Mark and use the same mounting bolt (located behind the A/C evaporator and blower module) for the heater assembly during the installation process. Other mounting bolts are longer and will obstruct the operation of the temperature door.
•Install the heat/vent module mounting bolt through the blower motor resistor or service access cover opening.
Tighten
Tighten the heat/vent module mounting bolt to 4.5 N·m (22 lb in).
•On vehicles without automatic climate control, install the blower motor resistor. Refer to Blower Motor Resistor Replacement .
•On vehicles with automatic climate control only, install the service access cover.
•On vehicles with automatic climate control only, install the service access cover mounting screws.
•On vehicles with automatic climate control only, install the outer layer of the A/C evaporator and blower module. Refer to Blower Motor and Fan Replacement .
•Refill the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
•Install the instrument panel. Refer to Instrument Panel
Remove the heater/vent module. Refer to Heater/Vent Module Replacement .
•Remove the heater core access cover screws.
•Remove the heater core access cover.
•Remove the heater core from the heater/vent module.
Installation Procedure
•On vehicles equipped with a manual transmission, remove the shift lever.
•On vehicles equipped with an automatic transmission, perform the following steps:
2.1. Apply the park brake.
2.2. Insert the ignition key and turn the ignition switch to the RUN position.
2.3. Depress the brake pedal and shift the transmission to the 1 position.
2.4. Turn the ignition switch to the OFF position.
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.
For Vehicles equipped with OnStar® (UE1) with Back Up Battery:
The Back Up Battery is a redundant power supply to allow limited OnStar® functionality in the event of a main vehicle battery power disruption to the VCIM (OnStar®module). Do not disconnect the main vehicle battery or remove the OnStar® fuse with the ignition key in any position other than OFF. Retained accessory power (RAP) should be allowed to time out or be disabled (simply opening the driver door should disable RAP) before disconnecting power. Disconnecting power to the OnStar® module in any way while the ignition is On or with RAP activated may cause activation of the OnStar® Back-Up Battery (BUB) system and will discharge and permanently damage the back-up battery. Once the Back-Up Battery is activated it will stay on until it has completely discharged. The BUB is not rechargeable and once activated the BUB must be replaced.
•Disconnect the battery negative cable.
•Remove the left sound insulator. Refer to Instrument Panel Insulator Panel Replacement - Left Side .
•Remove the right instrument panel sound insulator. Refer to Instrument Panel Insulator Panel Replacement - Right Side .
•If the vehicle is equipped with a multiple CD changer located in the center console, remove the center console. Refer to Front Floor Console Replacement .
•Remove the center sound insulator. Refer to Closeout/Insulator Panel Replacement - Center .
•Remove the lower left instrument panel mounting bolt.
•Remove and retain the instrument panel storage compartment. Refer to Instrument Panel Compartment Door Replacement .
•Remove the lower right instrument panel mounting bolt.
•Remove and retain the left and right speakers and the speaker grilles. Refer to Radio Front Speaker Replacement in Entertainment.
•Use a flat-bladed tool in order to remove the windshield defroster grille. Retain the grille and the sunload sensor (if equipped) for use on the next IP carrier.
•If the vehicle is equipped with a sunload sensor, twist the sensor ¼ turn counterclockwise in order to disengage the sensor.
•Disconnect the brown electrical connection from the body control module (BCM).
•Disconnect the purple electrical connection from the body control module (BCM).
•Remove the knee bolster. Refer to Knee Bolster Replacement .
•Remove and retain the instrument panel cluster. Refer to Instrument Cluster Replacement .
•Remove and retain the radio. Refer to Radio Replacement in Entertainment.
•Remove and retain the HVAC control assembly. Refer to the appropriate procedure:
• Control Assembly Replacement in Heating and Ventilation (Non-A/C)
• Control Assembly Replacement in HVAC Systems with A/C - Manual
Caution: This vehicle is equipped with a Supplemental Inflatable Restraint (SIR) System. Failure to follow the correct procedure could cause the following conditions:
• Air bag deployment
• Personal injury
• Unnecessary SIR system repairs
In order to avoid the above conditions, observe the following guidelines:
• Refer to SIR Component Views in order to determine if you are performing service on or near the SIR components or the SIR wiring.
• If you are performing service on or near the SIR components or the SIR wiring, disable the SIR system. Refer to Disabling the SIR System.
•Disable the passenger side SIR system. Refer to Disabling the SIR System in SIR.
•Remove the left and right instrument panel driver knee bolster brackets.
•Lower the steering column for clearance. Refer to the appropriate procedure:
• Steering Column Replacement in Steering Wheel and Column - Standard
• Steering Column Replacement in Steering Wheel and Column - Tilt
Important: Label all of the connections in order to avoid improper installation.
•Remove the top instrument panel screws.
•Roll the instrument panel down.
•Disconnect the electrical connections, as needed.
•Remove the fastener that retains the radio antenna cable to the instrument panel.
•Remove the instrument panel from the vehicle.
•If replacing the instrument panel carrier, retain parts for assembly of the new instrument panel carrier.
Installation Procedure
•Install retained parts from the original instrument panel.
•Install the instrument panel to the vehicle.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
•Install the fastener that retains the radio antenna cable to the instrument panel.
Tighten
Tighten the fastener to 1.9 N·m (17 lb in).
•Connect the electrical connectors, as needed.
•Roll the instrument panel up.
•Install the top instrument panel screws.
Tighten
Tighten the screws to 1.9 N·m (17 lb in).
•Raise the steering column into position. Refer to the appropriate procedure:
• Steering Column Replacement in Steering Wheel and Column - Standard
• Steering Column Replacement in Steering Wheel and Column - Tilt
•Install the left and right instrument panel driver knee bolster brackets.
Tighten
Tighten the screws/bolts to 6.3 N·m (56 lb in).
•Enable the passenger side SIR system. Refer to Enabling the SIR System in SIR.
•Install the HVAC control assembly to the instrument panel. Refer to the appropriate procedure:
• Control Assembly Replacement in Heating and Ventilation (Non-A/C)
• Control Assembly Replacement in HVAC Systems with A/C - Manual
•Install the radio. Refer to Radio Replacement in Entertainment.
•Install the instrument cluster. Refer to Instrument Cluster Replacement .
•Install the knee bolster. Refer to Knee Bolster Replacement .
•Connect the purple electrical connection to the body control module (BCM).
•Connect the brown electrical connection to the body control module (BCM).
•If the vehicle is equipped with a sunload sensor, install the sensor to the defroster grille by twisting the sensor ¼ turn clockwise.
•Install the windshield defroster grille by carefully pressing the grille into place.
•Install the left and right speakers and the speaker grilles. Refer to Radio Front Speaker Replacement in Entertainment.
•Install the lower right instrument panel mounting bolt.
Tighten
Tighten the bolt to 11.5 N·m (102 lb in).
•Install the instrument panel storage compartment. Refer to Instrument Panel Compartment Door Replacement .
•Install the lower left instrument panel bolt.
Tighten
Tighten the bolt to 11.5 N·m (102 lb in).
•Install the center sound insulator. Refer to Closeout/Insulator Panel Replacement - Center .
•Install the right sound insulator. Refer to Instrument Panel Insulator Panel Replacement - Right Side .
•Install the center console to the vehicle, if removed. Refer to Front Floor Console Replacement .
•Install the left sound insulator. Refer to Instrument Panel Insulator Panel Replacement - Left Side .
•Connect the battery negative cable.
•On vehicles equipped with an automatic transmission, perform the following steps:
26.1. Turn the ignition switch to the RUN position.
26.2. Depress the brake pedal and shift the transmission to the PARK position.
26.3. Release the park brake.
•On vehicles equipped with a manual transmission, install the shift lever.
•Install the heater core to the heater/vent module.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
•Install the heater core access cover.
Tighten
Tighten the heater core access cover screws to 1.9 N·m (17 lb in).
•Install the heater/vent module. Refer to Heater/V
