PhLaXuS

OK...I tried replacing mine sometime around last May because it was leaking. I fought to get the old one out and absolutely could not get the new one in. I ended up bypassing the core and returning the new one to the auto parts store. I bought another heater core yesterday and tried popping it in today. Here's a few tips that I found:

1.) Remove the passenger's side plastic panel.
2.) Pull the ECM
3.) Remove the 2 screws holding the ECM carrier into the dash, pull the carrier.
4.) Remove the 4 screws securing the heater box cover. It may help to pull the dash pad and remove the two main (I think 10mm) dash bolts which secure it to the car and also the ~4 small screws which also hold the dash to the vehicle. This will allow the dash to be pulled forward 1" - 3" and helps a bit with that top heater box screw.
5.) There are 4 screws securing the heater core carrier to the box.
6.) Heater core/carrier assembly pulls straight out once the hoses have been removed in the engine compartment.

Now...why I couldn't do it earlier this year: I'm an idiot. Once I opened the heater box, I only saw the two screws on the right side of the heater core "carrier". Due to the design, it looked as though I was only supposed to remove these two and then hinge the carrier open to replace the core. This is totally wrong. The carrier is to be completely removed from the vehicle to replace the core. After getting pissed off and declaring that I will not go through this winter without heat, I pulled on the carrier pretty hard. It (broke and) came out and to my surprise, I saw two screws were still holding it to the box! It's not supposed to hinge like I thought, but I didn't see the two screws on the left-hand side of the carrier. If it gives me any problems, I'll replace my broken carrier with a junkyard piece.

Knowing this little bit of info, it sounds rather easy to replace a heater core in a thirdgen...I suspect others who've had problems probably did the same thing I did because those two screws on the left side of the carrier are very much hidden unless you have a flashlight.

Hope this helps!

Sisco

Good post, I would recommend using care when removing the small screws that hold the dash in place. The metal clips on the back holding the plastic to the sheet metal often strip if you are not careful. Once they strip they are a pain the to get out.

Rick

Guest

I dont know about your car, but I just changed one on my 89 GTA. All the bolts except one were easily removed from below. The one 'tough' bolt (we all know which one)... well.. I removed the little black box (I still dont know what that thing is) and its bracket that resides behind my dash 'glove box' and ran an extension right through there. Easy. There's a rather large gap between the dash plastic and the lower support brace that everything attaches to like that box, the ecm, relays, and other various devices. I didnt notice it before, but was plain as day to me this time around.

Vader

If the core restraint bracket gives you trouble, you can remove it and weld the plastic. Dealing with 20+ year old plastic on several vehicles has created a need to learn to successfully repair plastic. It's only going to get worse (better?).

Tripper511

These are the intructions according to the Chilton Repair book:
<P><U>TO REMOVE:</U>
1.Drain the cooling system
2. Remove both heater hoses
3.Remove the lower right hush panel
4.remove the lower right instrument panel and the ESC module is necesasary
5.Remove the lower right instrument panel-to-cowl screw
6.Remove the heater case screws
7.Remove the case cover.
8.Remove the support plate and baffle screws,
9.Remove the heater core and baffle plate from housing.
<P><U>TO INSTALL:</U>
1.Position the heater core and baffel plate into the housing
2.install the support plate and baffel screws
3.Install the case cover
4.Install the heater case screws
5.Install the lower right instrument panel-to-cowl screw
6.Install the lower right instrument panel and the ESC module if necessary
7.Install the lower right hush panel
8.Install both heater hoses
9.Fill cooling system and check for leaks.

I bought the book for $10 on half.com. It has definitly paid for self a hundred times over!

PhLaXuS

Hmmm...I typically like Chilton's material. I didn't know those could be had for so little online...

Sisco

The Haynes Repair Manual says:

1: Disconnect battery

2: Drain cooling system

3: Remove heater hoses

4: Remove lower insulating panels from under the left and right side of the instrument panel

5: Remove the instrument panel pad

6: Remove retaining nuts from both front speakers

7: Remove the screws retaining the side window defrost ducts, the front carrier braces and carrier shelf and remove the side defrost ducts.

8: Carefully disconnect the ECM and set it aside.

9: Remove the radio trim plate, the upper console trim, and the glove box assembly.

10: Remove the parking brake handle grip, the screws retaining the console body, and position the console back out of the way.

11: Remove the trim plate under the steering column. Remove the two nuts retaining the steering column and carefully support the streering column out of the way.

12: Remove the bolts/nuts retaining the instrument panel to the cowl.

13: Move the instrument panel back far enough to access the heater module and remove the heater module cover.

14: Remove the screws retaining the heater core shroud to the module.

15: Installation is the reverse of removal.

Hope that will be of some assistance.

Rick

Guest

About 5,000 times.
At least Haynes will leave some kind of legacy behind them.

Sisco

Using the Haynes method at step 2, I drained my antifreeze (on the ground because it didn't tell me to do otherwise)

Once I got to step 15 it got a bit confusing because now you start backwards.. 14, 13, 12... 5, 4, 3, 2..?? How do I undrain my cooling system!!?!!?!?

Rick

Tripper511

You undrain your cooling system by reconnecting the hoses and filling your radiator with anti-freeze. But you don't really need to drain the whole system. I just disconnected the two hoses. Let the coolent come out and then burped the radiator when I intalled the new heater core.