The Plymouth Voyager's heater core is located in the rear quarter panel on the right side. If you need to replace the core, you must open up the quarter panel trim from the inside, which will require removing the middle seats in the van.
Unplug the cable from the Voyager's negative battery terminal. Drain the cooling system partially, using a clean container for possible reuse.
Take out the first and second row seats on the right side. Remove the trim panel on the sliding door sill, C-pillar and D-pillar, along with the quarter trim bolster and seat belt anchors for the removed seats.
Detach the right side quarter trim panel. Disconnect the trim by removing all screws and the hidden clips rearward of the sliding door. Unplug the accessory power outlet's electrical connector and pass the seat belts through their slots.
Disconnect the rear heater hoses from the heater core by removing the auxiliary clamps. Remove the core-to-chassis screws and lift the heater core (with the tubes) up out of the rear auxiliary housing.
Install the new heater core into the auxiliary housing. Replace the core-to-chassis screws, heater hoses and clamps.
Reinstall the right rear quarter trim panel, replacing the seat belts, electrical connector, quarter trim, seat belt anchors and the sliding door and pillar trim panels. Install the two right side seats.
Fill the cooling system (using new coolant may be best) and connect the negative battery cable. Run the Voyager's engine until it reaches normal operating temperatures. Observe the climate control operation and check for leaks.
