Welcome to JA,
Many procedures in this guide require you to "label and disconnect ... '' a group of lines, hoses or wires. Don't be lulled into thinking you can remember where everything goes-you won't. If you hook up vacuum or fuel lines incorrectly, the vehicle will run poorly, if at all. If you hook up electrical wiring incorrectly, you may instantly learn a very expensive lesson.
You don't need to know the official or engineering name for each hose or line. A piece of masking tape on the hose and a piece on its fitting will allow you to assign your own label such as the letter A or a short name. As long as you remember your own code, the lines can be reconnected by matching similar letters or names. Do remember that tape will dissolve in gasoline or other fluids; if a component is to be washed or cleaned, use another method of identification. A permanent felt-tipped marker can be very handy for marking metal parts. Remove any tape or paper labels after assembly.
In order to remove the heater core, you must first remove the HVAC unit housing, then disassemble the unit to remove the core.
If equipped with A/C, have the A/C system discharged by a reputable automotive technician utilizing a recovery/recycling machine before detaching the A/C system.
Remove the instrument panel from the vehicle,
See Figure 1
Disconnect and isolate the negative battery cable.
Using a suitable trim panel removal tool, carefully pry up and remove the top cover and cluster bezel.
Open the ash tray.
Use the trim panel remover to gently pry out and remove the center bezel.
Unfasten the 6 attaching screws from the across the forward portion of the right upper trim panel. Pull the panel rearward to disengage the 3 locator pins and remove.
Reach in and detach the wiring connector(s) from the rear window defogger and/or fog lamp switch(s) as required.
If equipped with Remove Keyless Entry (RKE), remove the 2 screws holding the module and lay over the instrument cluster.
Gently pull on the center A/C outlet duct to remove it.
Remove the 3 attaching screws from the corners of the control. There are 2 retaining in the front and one retaining from the top rear.
Pull the control rearward and detach the wiring connector.
Use a prytool to disengage the cable attachment clips, then remove the control in the vehicle.
Fig. 1: Exploded view of the control panel retainer locations
Drain the cooling system into a suitable container, then disconnect the heater hoses from the dash panel. Plug the heater core outlets to prevent coolant from spilling during unit housing removal.
If equipped with A/C, perform the following:
Remove the suction line from the expansion valve. Place a piece of tap over the open refrigerant line to prevent the system from being contaminated.
Remove the expansion valve from the evaporator. Place a piece of tap over the open evaporator fitting to prevent dirt and/or moisture from entering the evaporator.
Disconnect the rubber drain tube extension from the condensation drain tube.
Remove the 3 retaining nuts located in the engine compartment on the dash panel.
Fig. 1: Location of the 3 dash panel retaining studs
Unfasten the right side retaining screw.
Remove the remaining nut located on the dash panel stud.
Fig. 2: Unit housing retaining screw location
Detach the blue 1-way connector from the plenum. The module wiring harness must be removed with the module.
Remove the unit housing from the vehicle.
For right-hand drive vehicles, the unit housing does not separate. It is a one piece unit and must be replaced as an assembly.
Remove the clips and screws that secure the air distribution module to the evaporator/blower module. Then, separate the 2 units.
Fig. 3: You must remove the retainers, then separate the air distribution module from the evaporator/blower module
Remove the panel opening foam seal, demister opening foam seal, and heater core tube foam seals from the unit.
Unfasten the retaining clips and screws that hold the upper and lower housings together.
Fig. 4: Remove the upper-to-lower housing retaining clips and screws ...
Place the unit in the upside down position, then separate the two halves of the module.
Fig. 5: ... then separate the two halves of the module
Lift the heater core up and out of the case.
Fig. 6: Remove the heater core from the case
Place the heater core in the case.
Position the upper and lower halves of the module together, then secure with the retaining screws and clips.
Install the heater core tube foam seals, demister opening foam seal and the panel opening foam seal into the unit.
Position the air distribution module to the evaporator/blower module. Then, secure with the retaining screws and clips.
Install the unit housing in the vehicle.
Attach the blue 1-way connector to the plenum.
Install the nut located on the dash panel stud and the right side retaining screw.
Install the 3 retaining nuts to the dash panel in the engine compartment.
The remainder of installation is the reverse of the removal procedure.
To install: Control panel
Connect the cable to the control panel, make sure they are securely retained by the clips.
Attach the electrical connector to the control, then position the control in the vehicle.
Install the 3 control assembly retaining screws.
Install the center A/C outlet duct.
If equipped with RKE, reposition the module and install the 2 retaining screws.
Attach the wiring to the rear window defogger and/or fog lamp switch as necessary.
Fasten the right upper trim panel, making sure the locator pins are engaged, then secure with the 6 retaining screws.
Install the center bezel making sure the retaining clips are secured.
Close the ash tray.
Install the top cover and cluster bezel.
Connect the negative battery cable.
Have the A/C system evacuated, recharged and leak tested by a reputable automotive technician utilizing a recovery/recycling apparatus.
Hope this helps, an accept would be appreciated.