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Author Topic: 1984 Eldorado Heater Core Replacement  (Read 140 times)

Offline limikep

  • Posts: 13
    • CLC Member
      CLC Member #11110
  • Name: mpisciotta
1984 Eldorado Heater Core Replacement
« on: October 02, 2017, 08:11:29 AM »
Hello All,

I need to replace my heater core in my 1984 Eldorado.  I read my service manual regarding this but the part that states to refer to Section 8 to remove the instrument panel gets confusing.  How much and what part of the instrument panel needs to be removed.  I don't what to remove more of the instrument panel that needs to come off.  Thank you all in advance as you were very helpful in the past.

CLC #11110

Offline TJ Hopland

  • Posts: 6823
Re: 1984 Eldorado Heater Core Replacement
« Reply #1 on: October 02, 2017, 09:17:35 AM »
I saved this info from a post a few years ago in case I ever had to do one on one of mine.   I'm pretty sure it was for a 79-85 E car.   Sorry to who ever wrote it that I forgot to copy your name to give proper credit.  This car appears to have been a diesel so a few things like glow plug relay won't be there but the rest should be the same.   The apparent diesel confirms its 79-85 because there wasn't a diesel option for 71-78 which would have also been something I saved.

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. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline bcroe

  • Posts: 2057
    • CLC Member
      CLC Member #14630
1984 Eldorado Heater Core Replacement
« Reply #2 on: October 02, 2017, 08:00:22 PM »
Heater cores are on my 19 year maintenance schedule, to avoid failures. 
I did mine in a 79 Toro and later a 79 Eldo.  As I recall the manual starts
with "remove steering column and dashboard". 

I had no intention of doing all that, so I ran the right seat all the way back
(remove if not pretty skinny), dropped the column down a few inches onto
the seat, took out the dash bolts, hung the right side of the dash from a
wire, and pulled it back a few inches.  Crawled under there to get the heater
box out after unbolting, changed the core, and shoved it all back together. 
Not fun, probably less than 9 hours.  Bruce Roe

Offline limikep

  • Posts: 13
    • CLC Member
      CLC Member #11110
  • Name: mpisciotta
Re: 1984 Eldorado Heater Core Replacement
« Reply #3 on: October 03, 2017, 12:28:39 PM »
Thanks all for the feedback.  I had a feeling this was not going to be easy.  I will by-pass the heater core for now.  I only drive the car 500 miles a year and not below 30 degrees so I can deal with that for the 3 cold months where I am.  Thanks again.

Online James Landi

  • Posts: 687
  • 2007 XLR
    • CLC Member
      CLC Member #21920
  • Name: James Landi
Re: 1984 Eldorado Heater Core Replacement
« Reply #4 on: October 04, 2017, 06:54:31 AM »
I had mine changed out on my '83 4100 HT Eldorado five years ago at a radiator specialty shop... it cost me around 700 dollars in labor... the heater core was not very much at all.  I suppose a "work around" would have you put a small electric heater in your car over night.  I did that when I was using my Eldo in Maine during the winter months... kept everything warm and dry in the morning with so much less effort to remove "frozen accumulations."


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