Heater Core Replacement

Without Air Conditioning1. Disconnect the battery ground cable
2. Open the hood to access the front of the heater box on the passenger's side.
3. Disconnect the blower motor wiring and all other electrical connections from the front of the heater box.
4. You may or may not need to remove the windshield washer tank (depends on the year of your Fiero).
5. Disconnect the heater hoses from the heater core, then remove the heater core grommets. Be sure to plug the heater hoses so you do not loose too much fluid.
6. Remove the heater case cover attaching screws (#9) and the front cover (#18).
The heater core is now visible and remove the heater core retainer (#21). The old core can now be removed.
8. While the core is removed, take this time to clean the inside of the heater box and vacuum out any debris.
9. Reverse the procedure to install.



With Air Conditioning
1. Disconnect battery ground cable
2. Remove the subwoofer assembly from under the passenger side dash (if equipped), Figure 1.
3. Remove the convenience center that holds the chime unit, horn relay and flasher module. This unit bolts to the side of the heater box, Figure 1.

4. Pry the R/H dash speaker cover off and remove the four 7mm screws holding the speaker in place. Remove the speaker, Figure 2.
5. Place some towels or rags on the floor below the heater box to soak up any coolant that spills. Remove the four 7mm screws holding the heater core cover to the heater box. Three are accessed from below the dash while the 4th top screw is accessed through the speaker hole, Figure 3.
6. Remove the windshield washer tank and disconnect the two coolant hoses that connect to the heater core. Make sure to crimp or plug the hoses so coolant is not lost, Figure 4.
7. Remove the heater core retainer on the inside of the box and remove the core. Now is a good time to throughly clean and vacuum the inside of the box.
8.Reverse the procedure to install.