You'll know it's time to change your heater core when your heat starts smelling like coolant, and the interior windows fog up and even the AC won't prevent it. The good news is, there are only 2 screws that hold the heater core into the HVAC box!! The bad news is, it's going to take you about 4 hours to get to those 2 screws.
This writeup is how I did this job, it's not intended to be an exact step by step how to. This job is not for the faint of heart, or small of toolbox.
Now, on to the center console. On the B5, to remove the center console, you start in the back seats.
On to the dash
Time to move the center stack stuff.
Give it a try..
2. The airbag bracketes. The airbag sits on these, the dash will not come out with the bag bolted to these.
3. This is where the dash skin bolts to the frame. Not pictured is the center piece, at spot 3a.
4. The airbag module for the seats. Unbolt it from it's perch.
5. Remove these brackets. They hold the HVAC box in place in the center of the car. It's held in place on the far right side by the aluminum bracket. It's difficult to see in the below image, but behind the far impact absorber (in the red circle), there is a 3 angle bracket, which is held on by that impact absorber, and also bolts to the aluminum cross member, and the HVAC box.. Remove this bracket.
On to the HVAC box!!
Now, start putting things back together.
Reinstallation is literally the reverse of this proceedure, plus or minus. I'd really consider this more of a helpful hint article than a full blown how to, but I hope it helps you in some way, even if that is to dissuade you from destroying your car. I'd HIGHLY reccomend having the Bentley manual at the very least before attempting to change your own heater core.