Heater Core Replacement 83 Seville

[georgie49]

Looking for help in replacing the heater core on my '83 Seville. I removed the soft dash cover and about 20 fasteners from the hard plastic cover beneath the soft cover but it won't budge to get behind the dash.  Need advice from anybody who has successfully done this.  You can contact me directly at bergeng@sbcglobal.net. George Bergen  CLC#10261

[TJ Hopland]

Here is a run down I got from a guy that had just done it.  I think his car was an 80 Seville  but I could be wrong.  I know it was a 79-85 E body. The guys car was a diesel like mine so that is why there are some references to glow plugs and batteries. The glow plug relay is mounted on the passenger side fender.   The nasty thick insulation he talks about cutting through is a diesel feature.  I have not done it yet.  Mine is only still giving me minor whiffs that its leaking.  Let me know how it goes so I can add your notes to the procedure for when I have to do mine.



All hex heads are 7mm, except the firewall nuts, which are 12mm.

1. If you can, drain the radiator and block while the vehicle is level. Putting it on ramps makes draining the block easier, but if you suspect that stop leak has been used, keep the car level. The two block drain plugs are kind of hard to get to, and will shower you with coolant, so prepare for that.

2. Remove connectors to glow plug controller and relay.

3. Turn igntion to run, and set control head to 90 and econ. Listen for the programmer motor to stop.

4. After programmer motor has stopped, shut off the ignition.

5. Disconnect the negative battery cables.

6. Using a 7mm socket driver, remove the four hex head screws under the "lip" of the upper vinyl dash cover.

7. using a phillips #2 driver, remove the 4 screws at the defroster ducts.

8. Remove the upper dash cover by pulling out and up.

9. Remove lower dash hush panels and then remove the lower dash cover. You can remove the lower dash and ashtray as a single piece, though it is awkward.

10. Open the glovebox door and remove the liner, allowing you to gain access to the door screws.

11. Remove door.

12. Reaching through the glovebox, unsnap the air mix door link from the programmer arm.

13. Working on top of dash, remove 4 phillips head screws that hold the defroster ducting in place and pull them slightly up (1/4 inch is fine).

14. Unsnap the plastic clips that secure the center duct to the top of the dash. These are similar to the clips that hold the door panels on, so be careful with these.

15. Using the 7mm driver, unscrew the defrost ducting from the top of the HVAC case.

16. Carefully disconnect the programmer electrical connector from programmer.

17. Remove 2 screws from programmer that secure it to the HVAC case, and set programmer aside and away from the hvac box. You may have to disconnect the orange recirc door hose. Make sure that the programmer is not below the HVAC case.

18. Remove the screws securing the A/C duct intake to the HVAC case, and remove both it and the defrost uptake.

19. Working underhood, loosen the clamps holding the heater hoses to the heater core nipples, and remove the hoses.

20. Using a putty or insulation knife, carefully chip away at the 3 visible HVAC box studs on the firewall. The insulation will fly off in chunks, so eye protection is a good idea. 3 are located on the firewall under, beside and slightly above the heater core inlet.

21. Remove A/C power module from the evaporator case and set aside.

22. Using a 12mm socket, remove the 4 nuts securing the HVAC box to the firewall. The last one is inside the evaporator case.

23. Working inside the car, carefully pull out and down to remove the HVAC box from the firewall. When it comes off, it will go all at once.

24. Disconnect the vacuum hoses to the defrost and mode door actuators.

25. Remove HVAC box from vehicle and push open the mode door to look for antifreeze/coolant.

26. Working on the outside of the box, there should be 2 or 4 screws that hold the box together. Remove them.

27. Remove 4 phillips head screws and 2 clamps to remove the heater core.

Total time: 9 hours, including re-installation.