I just finished spending 2 days of my Christmas vacation replacing the heater core in my daughters car Ugh!!!

Here is what I learned;
1. Haynes manual is very inaccurate
2. To remove lower dash panels on both sides of car, remove speaker grilles to access bolts for panels, they pry out from top. also remove the switches or switch covers to the right and left of the steering wheel to access bolts for lower dash panel.
3. Remove center console, the lid needs to be removed and the junkbox removed to unplug the ect switch, warning light, also remove the seat belt release knob there is a small screw on side of it. Also unbolt the shoulder straps from the roof (remove center plug there is a 13mm (I think) bolt
4. remove center dash trim, radio, ashtray, center dash panel and a/c heater control. (see manual this is one area that it helps)
5. remove the metal side brackets that go from trans hump to dash
6. remove glovebox door and glove box
7. remove all ducts that connect to the heater box, there is 1 in the front,and 1 on the side and the lower floor duct. You do not need to remove the under the seat ducts just seperate them at the box, you also need to pull back both sides of the carpet behind the center console.
8. remove and unplug all wiring that run in front of the heater core and a/c box.
9. the manual claims that you dont need to remove the A/C evaporator box but my heater core was melted to the rubber firewall and it was not possible for me to remove it. with the A/C box out of the way I could get my hand behind the box and pry the core of the rubber Ugh!!!
10. I had the A/C system drained and disconnected the 2 lines and removed the rubber grommet from the firewall, I did the same thing for the heater core.
11. I also found that unplugging the wiring harness to the ECM which is on top of the transmission tunnel helped clear things out.
12. I unbolted the A/C box 2 nuts to the firewall and 1 or 2 to the heat box and remove the A/C box the drain line on the bottom will pull out so remember to feed it back in when you reinstall it.
13. remove the 4 or 5 nuts for the heater box there are 2 at the top that are difficult to see but they are there! Remove the heater core box. I took mine out through the pass side as the A/C box was already out.
14. there are 2 clamps that hold the piping in place for the core and then the core slides out of the top of the box. I purchased the core from Auto Zone ($65) as the Dealer wanted $400, the car itself isnt worth $400 LOL.
There 2 extension pipes that you will need to reuse and they are clipped together and a rubber O ring to seal it.
Of course the cheap one doesnt fit as well and I wasnt going to trust those clips and O rings to hold, so I cleaned the fittings very well and soldered them together with plumbers solder for a little piece of mind.

Sorry there are no pictures but I only decided to write this after my blood pressure came back down and thought it maybe a good time to at least write down what I remembered! I hope this helps as my search on the subject didnt yield anything in depth.

Of course just reverse the process to reinstall. Hopefully you have a clean dry place to do this work and if it is cold hopefully some heat. I truly appreciated my heated garage for this project.

http://www.toyotanation.com/forum/showthread.php?t=325937