Tech Article Title Author Date
Heater Core Swap Greg Kiernan 2005

I just got finished with my heatercore R&R, easily the biggest headache i've had with my car to date. There was no good, detailed writeup for the procedure. So I took some pictures as I was putting the car back together. I'll try to make this as detailed as possible. This is a major undertaking, not difficult at all, just very tedious. It will help alot to have a friend help you on some of the parts. To give you an idea of what you are about to do to your car, here's a picture of everything your going to need to remove from your car to replace your heatercore:

Scared yet? Don't be it's not that bad (famous last words :o\ ). These are the tools i ended up using:

-long necked screwdriver
-Phillips head screwdriver
-Flat head screwdriver
-Breaker bar w/ a 15/16" socket
-A set of Allen Wrenches (you'll use the 4mm one alot)
-A decent rachet set (you'll use the 8mm, 10mm, and 13mm sockets the most)
-A long extension for the rachet
-A set of Metric wrenches that goes all the way down to 8mm
-An extending magnet, your most likely going to drop a screw or 2, and this comes in handy in tight areas.
-A T30 torx bit
-A small mirror

Ok got all your tools? Time to get started. Keep in mind that this was done on a 1993 90CS with automatic climate control and an automatic tranny and that I took the pictures while reinstalling everything.
First put your drivers seat all the way back, and lay the back as far down as possible. You need to remove the panel that surrounds the E-Brake. There is 1 8mm bolt under a cover at the front of the panel, and a 13mm nut under a cover at the rear of the panel.

To remove the panel, pull the ebrake as far up as possible and slide the panel up the brake until it's free. Most of the panels in the car are very resilient so if you need to force that panel a bit it should be ok. Next is the panel below the dash that wraps around the shifter. To remove it, lift up on the panel near the shifter and wiggle the whole panel up and over the black gear selection display (it helps to have the transmission in a gear to give you some extra clearance). Then pull the panel towards the rear seats to release it from the clips that were holding the front of the panel. With that off, look under the dash at the driver's side. You'll find a large panel that stretches from the firewall to the steering wheel. To remove that, there are two bolts at the top of the panel with round covers over them. To remove the covers, slip a flathead screwdriver in the side of them and pop them out. After those 2 bolts have been removed there are 2 more at the bottom corners of that panel, the panel will then slide out towards the driver's seat. Now, you're going to be working with your airbag system which can be dangerous if not done correctly. First disconnect your battery, then look under the dash again where that panel was, you'll see a small red connector, that goes to the driver side airbag, disconnect that. Now, move over to the passenger side under the dash. There is a panel that goes from the firewall to the glove box that is held on by 2 bolts located at the very edge of the glove box. Once that's out, move onto the glove box. Open the glove box and you'll see on each side there are 2 bolts

Once all 4 of those bolts are out, to remove the box, shift it all the way to the left and get the right side tabs to drop out, and then just slide it out towards the passenger side door. Time to start taking the dash out. Your going to start at the steering wheel. If you have the steering wheel straight, look behind the wheel, you will see 2 bolts, one on either side, they require a T30 star bit to remove. Once they are fully backed off the airbag should come right off of the wheel. On the back of the airbag you will find a connector under a clamp.

unhinge the clamp on one side and remove the connector, the airbag can then be placed aside. Now take the breaker bar and the 15/16" socket and fit it too the nut in the center of the wheel. Loosen it with the bar, and then just take it off. Don't remove the wheel just yet, look underneath the steering column, you'll see 3 holes,

in the 2 holes on the sides of it there are 2 screws you need to remove. Once they are out remove the top half of the steering column cover and look for another red set of connectors for the air bag.

Disconnect them and then you can slide the steering wheel off. Now under the steering column, look inside the middle hole, there is a bolt that needs to be LOOSENED, not removed!, it requires a 4mm allen wrench. With that loosened, you can slide the remaining part of the steering column switches off and disconnect all of the wires connecting too it. You can label the connectors if you want but they are all color and shape coded so you really can't put them back in the wrong way. With the switches out you can now move onto the gauges. You'll see 2 phillips head screws at the bottom of the gauge pod, remove those and it'll come right out. Whenever i remove a screw i try to replace it in the same place so when you have to reinstall everything you'll know what screw goes where(as you can see in some of the pictures). You need to carefully remove all of the wires that are connected to the gauges and set them aside. Your dash should now look like this:

Now it's time to move to the center of the dash. You need to first remove the air vents. The best way that i found to do that was to slide a flat head screwdriver underneath the vent and pry it up slightly, then gently wiggle the bottom of the vent out. Once the bottom is out, the top will drop right out. Remove all 3 vents. Now remove the switches by popping them out individually. To get them out, put a flat screwdriver in-between the switch body and the small trim piece around the switch and turn the screwdriver. Do this on both the top and the bottom of the switch and that should move it out far enough to grab it and pull it out the rest of the way. Once the switch is out, disconnect the wire by firmly grasping the switch and the wiring harness and pulling them apart (don't pull by the wires!).

Once they are all out you can remove your radio, stock or aftermarket, mine is an old aftermarket that came with the car so I don't know if removing the stock one is any different. To remove the A/C controls, first pop off the trim panel around it with a flat screwdriver. Then you will see 2 bolts inside the clips that held the trim on, remove those and the A/C controls. At this time you can also remove the ash tray if you have one. To do so you'll see 2 screws just below where the A/C controller's bolts were, take those out and then pry the carpet off of the bottom of the ash tray, this will expose 2 more bolts that you need to remove at the very back, underneath the ashtray. Now the entire center of the dash should pretty much be stripped. At the 4 corners of the opening, you'll see 4 bolts. Remove those and then the mounting bracket should come out leaving a large rectangular hole in the dash.
On the side of the dash near the doors, there are 2 bolts on either side hidden behind the same type of covers as seen before.

Remove those bolts, and then look at the bottom of the dash near the transmission tunnel. You should see 2 bolts on each side that you need to remove.

With these 8 total bolts out, your dash should be loose enough to lift out of place. This is where it helps to have a friend around. The dash is not heavy, but it is massive and is much easier to maneuver inside the car with 2 people. Before the dash can be completely removed, look behind the passenger side of the dash. You'll see the passenger side airbag, disconnect all the wiring that goes to that and then you can fully remove the dash from the car.

Now that the dash is out, I highly suggest you wrap the steering column with something soft, because your probably going to whack your head on it a few times (if you haven't already). Now look to the center part of the large duct that is left attached to the car, you'll see 1 bolt, remove that and it'll come right off.

Now look to your left and you'll see a large gold colored bracket, you need to remove that by taking out the 3 bolts that hold it in place

Next is the metal bracket that spans over the 2 rear footwell air ducts. There is a bolt on each side of it that needs to be removed, to reveal them you may need to pry back the carpet a little bit.

Now you need to remove the air ducting. To do this first remove the screw at the very back of the lower duct on the driver's side. This is where the long phillips head screw driver is helpful, you can get the screw by reaching around behind the pedals.

Then remove the 2 screws that hold the small middle ducting in place

Now you can remove that middle ducting piece be pushing it down and prying the top out. With that piece out you can then maneuver the front footwell ducting away from the rear footwell ducts. It actually splits into 2 pieces so you can remove half of it on each side. With all of the surrounding ducting removed, you can begin on removing the wiring on the heater box (remember I did this on a automatic A/C, manual controls may be different). All of the wiring on the heater box is held to it by brackets, these brackets can be removed to help you disconnect the wires. Once all of the visible wires are removed from the heater box pop the hood, time to get dirty :o) . Release the pressure in your cooling system before you do this. Draining the system would help keep things a little cleaner but I didn't find it necessary. Loosen the clamps that are holding the coolant hoses onto the heater core pipes going into the firewall and keep those hoses out of the way until you are ready to install the new heatercore. Right to the left of the heatercore pipes is a nut with a washer and round rubber gasket on it, remove that. Also there is a large rubber gasket around both pipes leading into the firewall that needs to be removed.

Then look about a foot straight down from that nut and you will find another. This lower one is tricky to get out and is a good place to exercise that extending magnet so you don't loose that nut. Just be patient and you'll get it off with a wrench or socket.

With the 2 nuts, the gasket removed, and the hoses off you can move back into the car. There are 6 clips that hold the heater box to the evaporator box. 2 in the front, 2 in the back, 1 on top and 1 on the bottom. You need to pop off the clip on the top, the 2 in the front, the 1 on the bottom, and the lower one in the rear. That lower rear one is VERY difficult to get out, you just need to get creative with that mirror of yours, a flashlight, and some sort of tool to pop off the clip. It is a very tight space that you have to work in, but it can and has been done. I used 2 very small screwdrivers, one small enough to wedge under the clip to prop it up a little bit, and the other to pop the clip off. Ok so that's 5 clips, what about the 6th? well don't worry about that 6th clip, the box should have a good 1" or so of play in it now, just grab it firmly and wiggle it around, that last clip will work it's way off and then you've done it. The heater box should now be free. To gain some extra latitude in moving it out, i unbolted the airbag sensor that is inbetween the 2 rear footwell ducts. With all of that out of the way, you can pull the heater box out and finally take that old heatercore out. The heatercore is held in with 2 screws and 2 clips on the ends. Just remove/release all of those and it'll come right out. With the new heatercore installed, time to put that huge pile of parts you've accumulated back into the car. Just work in reverse order from what has been written above. I did have a little trouble at first getting the heater box and the evaporator box to line up right. It helped to open the front "door" on the heater box, this allows you to reach inside and aid the 2 pieces in lining up. Once they are meshing correctly, you can put on at least the front 2 and the bottom clip. The box holds very firmly with just those 3 clips. After you get the heaterbox in, everything pretty much will fit right back into place without much trouble. Alright that's all there is too it. It'll take up a full weekend easily so be prepared. Congratulations, you now have heat :o)

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