It is a crappy job but you feel good once it's done. Loosely this is what I had to do (Gen 1 dash instructions).
- Remove the lower molding on the front passenger and driver side. You may need to remove the upper molding too.
- Pop the dash speaker covers off with a flat-head screw driver and unplug the EATC and headlight connectors if they exist (remember which side goes where). This is a good time to hook up extra speakers in front.
- There are three or so screws holding the top of the dash in to the body which you will need to remove. There may also be some on the side under the moulding that you took off earlier.
- Now you will have to take off the steering column kick guard, the dash bezel, the EATC, the radio, the clock and anything else that is connected to a wiring harness. Don't lose the nut off the back of the EATC air feeds, and don't lose the nut off of the headlamp dial. They will be a pain to find replacements for.
- Remove the screws holding the carpet/wire cover near where your passenger's right foot should be.
- I took the steering wheel off but it may be possible to do this with it on, but you will have to drop the steering column. There are four nuts on long studs in a square pattern right underneath the kick guard you took off. This will remove a bracket. Keep the nuts with the bracket. Under that bracket on the same studs are four more nuts holding up the column. You may also need to remove the intermediate shaft bolt but I'd try to do this without removing it if possible. Remember how the bracket goes on the studs as I didn't and it gave me a lot of grief. Also, the nuts that hold the bracket on are different sizes than the ones that hold the column up.
- Under where the bezels used to be there are three or four screws/bolts holding the dash onto some metal brackets that need to be removed.
- You may need to pull the cluster if the dash wiring connected to the cluster is impeding the removal of the dash. There are four brass(?) screws holding the entire cluster assembly down and two fat connectors plugged into it. Also, the speedo cable needs to either be removed from the tranny(?) or from the cluster when pulling the dash. I suggest not pulling it from the cluster. It was a pain to get it back on.
- This is where it is helpful to remove seats. You need to get upside down and remove the two screws holding the floor HVAC snorkel in. It is located right behind the center console almost against the firewall. This had me stumped for a while but it's fairly easy to remove just sorta difficult to reattach.
- You'll have to detach the e-brake release handle. I didn't do this because my car didn't come with one.
- Check around for any more bolts or screws holding the dash in to the firewall/bracketry. Jostle the dash loose. If you have everything off you can start inching it backwards. The HVAC plenum is right not quite centered behind the dash; you can access most of it from the passenger side.
- There are some flexible tubes that will need to be disconnected from the blower control module (BCM) on the plenum, as well as connectors running to the blend door motor (BDM) and the fan.
- Wiring is the biggest pain in this whole trek. The harnesses are thick and everywhere and will always get in your way. There should be only one place you need to remove the wiring from the dash and that is underneath the passenger foot area when you pull out the dash slightly, a thick bundle of wires is connected to the dash by way of those little plastic pressure fittings. They are just a little piece of plastic pushed through a hole in a metal bracket. Just put your fingers around each side of the harness and yank until it comes out of the hole. None broke on me but plastic ages at different rates so you may need a backup plan if the plastic snaps off. You should be able to get away with yanking off three or four of those connectors, or about the distance to the ashtray.
- If my directions are not that far off you should be able to pull the passenger side of dash farther out. If not look through the windshield into the area behind the dash for more wires or hoses and check the from of the dash for more bolts and screws.
- You must remove that friggin' snorkel that runs HVAC to the back seats I talked about earlier.
- Once you can get the dash back you should see this attached to the firewall:
Well, that is from the drivers side, but you get the idea. To my recollection the numbers mean:
1: AC Evaporator core (cheap! Replace now!)
2. Heater core (replace!)
3. Vacuum hose
4. Vacuum actuator (opens the passenger side vent)
5. Evaporator core in (or out, I have no idea)
6. BCM hose
7. BDM (replace if at all possible. I couldn't find it at all for my 90)
8. Blower motor power connector
9/10. BCM and BDM connector, forgot which was which, but it is easy to tell when apart).
When I got this far I replaced everything I could. The blower motor was about $30 from Schucks (you have to reuse the squirrel cage), the heater core was $50 from a local parts store, the BCM was found used on the forum, and the BDM was not replaced because the design was discontinued for my year and none of the current parts worked. I also reglued both halves of the plenum with heater glue and replaced all the screws. I didn't replace the evaporator because I'm stupid.
- So at this point you will need to remove the bolt at the top of the unit attaching it to the chassis. You will then need to go the the firewall on the engine side and remove the three nuts with big round flanges holding the plenum to the firewall, as well as getting a special AC tool from a parts store to remove the spring fittings from the two AC lines on the evaporator. I cut them off because I get fed up with my stupid tool and just took the plenum to a repair shop to have them take the fittings off. Who needs A/C anyway?!
1/2. A/C in and out, don't ask me which one is which, though if someone would tell me I can edit this later.
3. Heater core in and out, same as above.
4. Vacuum hose
5. Blower motor
6. The studs that poke through the firewall with the three large flanged nuts on them.
These pics are the "before I cleaned it all up" shots.
- Remove the heater core hoses and the vacuum hose and you can now pull the plenum out. I suggest if you are this far into it spend $100 or $150 and replace as much as you can with quality new parts.
- Installation is reverse of removal.
A few tips though.
1. Remove the ash tray. It'll help.
2. Remove the snorkel. This job won't happen without it.
3. When installing the new heater core, the felt that ran around the perimeter of the core was all squashed so I picked up some more from a hardware store that was rated for higher temperatures. I think it was some sort of RV felt tape.
4. It takes two people to position the heater core when reinstalling it into the firewall.
5. It also takes two people to properly install the dash.
6. Important! When installing the dash the harnesses for the EATC diode and the headlamp auto on diode like to hide. Do not screw the dash back in until you have those wires ran through the holes under the speaker grating. Use some masking tape to hold them there.
7. Reinstalling the snorkel is a big pain because of alignment issues but is much easier with no ashtray.
8. Have a helper position the dash while you plug in the BCM hose and the plenum electronics.
9. Use the windshield, preferably with no glare. It is invaluable to be able to see behind the dash when it is being uninstalled and reinstalled.
10. Don't forget to reattach the wire bundle that runs under the dash by the passenger's foot area.
11. When putting the steering column back on have a friend hold the column or steering wheel. It's heavy and the studs are at least two inches long.
12. Take your time. I'd suggest before finally reattaching the dash to plug the power in and test the electronics.
Now this can't be all complete because it's been a couple years since I did this but if anyone has anything to add, by all means post it and I'll edit my post.
