Changing the heater core in a 1998 Jeep Grand Cherokee yourself can save you quite a bit of money. The act of changing the heater core itself can be done fairly quickly, but what has to be done to get to that point is what takes most of the time in this project. Set aside the better part of a day to get this job completed because each step involves a great deal of removing and reattaching screws.
Apply parking brake and chock the wheels to keep the vehicle stabilized while you work. This can be done by placing a block of wood behind the tires to keep them from rolling.
Disconnect the ground wire from the battery with pliers or wrench. Discharge the air conditioner.
Place large container under radiator to catch the coolant. Remove the plug to drain the radiator with a socket or wrench. Loosen the radiator cap for a more even flow.
Replace the radiator drain plug and cap and move the container to underneath the engine block. Drain coolant from engine block by removing the drain plug with a socket or wrench. Replace drain plug. It may be necessary to remove and drain the coolant reservoir as well.
Loosen the clamps on the heater hoses with the flat-head screwdriver.
Remove the dash or instrument panel with a Phillips screwdriver; then open and remove the glove box. On the left side behind the glove box are the remaining screws for the instrument panel. Finish removing instrument panel and disconnect all of its electrical parts. Remove the panel from the vehicle for more working room. This may take two people. Lower the steering column into the front seat for support.
Pull the carpet back in the center of the vehicle under the dash until you can get to the bolts on the panel brace. Remove those bolts to loosen the console and remove the console. At this point, it is likely necessary to remove the radio as well by disconnecting the wiring from the rear of the device and loosening the screws on the front.
Disconnect the heater and A/C vacuum lines by loosening the clamps. Disconnect electrical wiring from the A/C unit. Disconnect the computer from the firewall, but do not disconnect the 60-pin connector.
Remove the heater core from the housing using a Phillips screwdriver. Install new heater core and reattach with screwdriver. Reassemble everything in reverse order of how it was removed.
