First off, I need to give you fair warning: Removing your heater core is a very involved process. And if you haven't done this before, I don't recommend you do this by yourself.
Now if you would like to tackle this job anyway, I suggest you purchase a repair manual for your vehicle or subscribe to an on-line service such as " AllData" or " Mitchell 1".
These will give you detailed instructions as well as pictures, a list of hardware/tools required and helpful hints and tips.
The involved process I speak of must begin with the recovering of your a/c refrigerant. This means you have to empty your a/c system of R134a because your " Evaporator" is located in the same place as your " Heater Core", and the removal of the heater core requires the complete removal of your HVAC module assembly, which is located under your dashboard. This will require the removal of your upper dashboard, the a-pillar trim panels, the center console, passenger side kick panel, and a few more small but difficult items.
And all of this must be removed just to get to the HVAC module. Once you have the module removed from the car, there'll be several more pieces connected to the module that'll have to be removed before you can access the heater core.
This is why a shop will quote you an " astronomical" price to service this unit. The mechanics aren't lying to you when the say it'll be " EXPENSIVE"!
Here's the procedure you're looking for. Sorry I can't provide illustrations. (Buy that service manual)
HEATER CORE REPLACEMENT
Remove the HVAC module assembly.
Remove the lower center floor air outlet duct.
Remove the upper center floor air outlet duct screws.
Remove the upper center floor air outlet duct.
Drill out the heater core cover heat stakes.
Remove the heater core cover screws.
Remove the heater core cover.
Remove the heater core.
Install the heater core.
Install the heater core cover.
Install the heater core cover screws. Tighten Tighten the screws to 1.5 N.M (13 lb in).
Install the upper center floor air outlet duct.
Install the upper center floor air outlet duct screws. Tighten Tighten the screws to 1.5 N.M (13 lb in).
Install the lower center floor air outlet duct.
Install the HVAC module assembly.