So, your heat blows cool / cold out of the passenger side and you want to get nice even heat? Here is how to do it.
Be warned, this is a pretty time intensive job. I did it over the course of a few days. It can be done in a day for sure though. I also did this two months ago, and I'm sure I don't remember every detail. Basically, you just have to keep pulling stuff apart until you can get to the heater matrix. I highly recommend taking pictures as you go because there is a lot to disconnect and reconnect.
Lets get started!
First, disconnect your battery. I highly recommend keeping your battery disconnected for the entirety of the repair. If you power your car up with your airbags disconnected, you'll have to have the code reset at a dealer (or possibly with ETACs decoder). Its much easier to just keep the battery disconnected until you're done.
Now, lets remove the center console. Remove the push pins towards the front of the center console. To remove them, use a screw driver or something somewhat pointy and push the center in. With the center pushed in you can pull them out. There is one on each side.
Use your flat bladed screw driver to pop open the little cover on the back of the center console. You will see a 10mm bolt there to remove.
Pull up on the panel under the parking brake lever to expose another 10mm bolt to remove. The panel should pop out with relative ease. If you have plastic interior tools, I would recommend trying to pull it open from the front or sides as it'll be slightly less stressful on the rear clips.
Unscrew the shift knob to remove it.
You can now remove the center console. You will need to have the parking brake lever pulled up so you have enough clearance to remove it.
Next up is to remove your glove box. To do this, open it and press the two outer edges of the glove box together and it will flip down farther. After it flips down, you can pull it off.
Now, we are going to remove the radio and heater controls. Start with the top section. Using plastic trim tools is a nice way to get these out without marring up surfaces.
Remove the screws holding the stereo in place. Then, pull the whole lower section out. You'll have a bunch of stuff to disconnect so be careful not to just yank it out.
Now, lets move on to the gauge cluster. The trim piece just pulls straight off. This exposes a philips head screw. Remove this and the gauge cluster can come out. I will have an electrical connector on the back to be disconnected.
Next up is the paneling below the steering wheel. I forget if there are bolts or screws to remove. But there is a left and right side that come off.
Remove the A pillar trim panels. These just pop off. You can leave them dangle unless they really get in the way.
Now, look in the area that your glove box used to be in. There are two bolts holding in your passenger airbag. Remove these two bolts and push up on the airbag to remove it from the dash. Be careful removing this piece as it does have sharp metal that can easily scratch up your dash.
On the back side of the airbag are the electrical connectors. You'll need a small flat blade screwdriver to pop up the center section on them to remove the connectors from the airbag.
Now, move back to the driver's side and remove the bolts around the driver's side knee airbag panel. There will be another airbag connector to remove on this airbag. Also, there are odd plastic clips holding the panel to the dash. I forget exactly how they come out, but they can be a pain to figure out. You have to pinch the clip the right way. I think one you have to pinch vertically and the other is horizontal.
Alright, time to remove the big dash piece! You'll have to go around and find the bolts that are holding it to the car. There really aren't that many though. There is one on each side by the A pillars, and also down below it. There are probably a couple around the center stack as well.
Okay, now lets drop the steering column down. Remove the four or 5 bolts that hold it up to the big metal support pipe. It will drop down. You'll probably want to unplug some of the electrical connectors going to the steering column as there isn't enough slack to let it down otherwise.
Now, we need to get that big metal bar out of the way. I never fully remove it from the car though since is a bit of work. You'll have to remove a bunch of wire harness connections from it. You'll have to remove the center support shown below. And you'll have to remove the bolts that hold it to the sides of the car.
We're getting closer now! At this point, you can pop the hood, and disconnect the hoses going to the heater core. This will require removing the airbox to get access.
Now, there are a few nuts holding the heater matrix to the firewall. These will need to be removed so we can pull it away from the firewall to pull the heater core out. I believe there are 3 on the top and one or two on the bottom.
Take a look at the left side of the heater matrix. You will see the heater core's two aluminum tubes coming out of it. Remove the electrical connectors that are in the way going to the actuators. You'll also have to remove the lower actuator from the matrix to get the heater core out.
Remove the two philips head screws holding the heater cores tubes.
Now, you can pull the heater matrix away from the firewall enough to pull the heater core tubes through. Once the tubes have released from the gasket, you can pull the heater core out of the heater matrix. The tubes on the heater core do swivel. So, take it in steps and remove it. I also suggest putting a towel down to collect any dripping coolant. You don't want your cabin to smell like coolant.
WOOHOO, you are finally half done!!!
Reassembly is really just putting everything back together. Follow the steps in reverse to do it all. Phew, it was enough work just writing all this. I highly recommend if you can get your dealer to do this, DO IT!