How to Replace the Heater Core in a 2002 to 2006 Dodge Ram 1500

by Chris Moore

The heater core is necessary to heat the engine coolant and produce hot air in your truck. Signs that you need to replace the core include sweet smells from inside, steam coming out the vents and coolant leaking onto the floorboard. On a Dodge Ram made between 2002 and 2006, you need to remove the heating/air conditioning unit from the truck to replace the heater core. This will involve removing the dashboard, which may require the help of at least one other person.

Removal

Step 1

Take the truck to a legal, licensed air conditioning technician that can correctly discharge the air conditioning system.

Step 2

Disconnect the truck's negative battery cable and then drain the engine coolant at the radiator's drain plug, letting it pour into a large container.

Step 3

Disconnect the heater hoses from the firewall on the right side, sliding away the hose clamps. Cover the firewall openings with tape or rubber plugs.

Step 4

Unbolt and detach the air conditioning accumulator and its bracket using your wrench. Disconnect the air conditioning lines from the evaporator.

Step 5

Unscrew and remove all trim panels on the instrument panel and the instrument cluster. Lower the steering column and disconnect all electrical connectors. Detach the hood release and parking brake handles, then remove the instrument panel's fasteners with your wrench. Lift and remove the instrument panel.

Step 6

Disconnect the electrical connectors for the powertrain control module, located on the right rear corner of the firewall. Remove the module's mounting bolts with your wrench, then remove the module.

Step 7

Unscrew and remove the two mounting nuts for the heater/AC unit within the engine compartment using your wrench, then disconnect the unit's electrical connectors and vacuum hoses from inside the truck. Remove the nuts and bolt from the interior and remove the heating/AC unit.

Step 8

Remove the heater core's two retaining screws at the top of its triangle-shaped evaporator tubes, then press the retaining tabs at the bottoms of the tube and lift the core out of its housing.

Installation

Step 1

Slide the new heater core into the housing, making sure its foam seals are all in place, and apply the retaining screws where the evaporator tubes come together.

Step 2

Install the heating/air conditioning unit within the interior of the truck using its nuts and bolts, hoses and electrical connectors from inside the passenger and engine compartments.

Step 3

Reinstall the instrument panel with its fasteners and reconnect all of its switches, the instrument cluster and its trim panels.

Step 4

Reconnect the powertrain control module and the air conditioning accumulator with its refrigerant lines to the evaporator. Reconnect the heater hoses to their fittings in the firewall with their clamps.