I love the way the germans keep all the fastners from being visible, but at the moment I'm cursing them. I'm trying to get the heater control out of the dash to replace the bulb. i can't figure out how to get the trim panels off so i can get to the controls. can someone help?
I have a '95 S420 and have been down this road to replace the controller.
Here's what you do...
Plan A - I think I remember that you can gently pop off the HVAC button or temp indicator in question, and change the bulb using some standard fishtank airline. You just slip a piece of the tubing over the offending bulb and use it as a wrench to unscrew the bulb. For confirmation, Google for it...I think I saw it on the internet somewhere.
If that doesn't work
Plan B -
2) If that doesn't work, start car and shift into 2nd to get the shifter out of the way. Turn off car.
3) Remove gear shift knob. Rotate bottom section of knob CCW (I think) about a 1/4 turn... knobs pops right off.
4) Remove black plastic trim ring around shifter. It pops right off, but ease it up bit by bit around the whole perimeter.
5) Unscrew wood trim plate on front of ashtray. Requires offset screwdriver and patience.
6) Cock the ashtray forward about half way...this exposes 2 torx head screws under the back lip of the ashtray hole. The screws point towards the back of the car and hold the lower wood trim to the upper. Find the right size torx wrench to break the screws loose, then go to the next smallest size to unscrew until you can get your fingers on them. You'll go nuts trying to re-engage the right size wrench for each 1/3 turn after they're free. IMPORTANT: Don't drop the screws down into the cavity under the wood trim panels...recovery is a major hassle.
7) Carefully pull BOTH trim panels up at the same time by holding the seam you just unscrewed together. The top of the vertical trim and the back of horizontal trim have little tabs that hold them down. By pulling both up at the same time in the middle, they will kind of "fold" at the seam and open up, releasing the tabs. I tried one at a time, and broke the tabs off the horiz trim...$646 for a new one. Also, try to disturb the back edge of the horiz trim piece as little as possible. At least on mine, the rear seat headrest switch connector loves to fall off. It's really annoying to go through all of this just to put the connector back on.
8) Pull them up just enough so that the vert trim just clears the horiz trim piece. Then push the very top edge of the vert trim piece into the dash, while pulling the bottom edge out and up. As the bottom edge comes up, the top edge will finally hit an angle where you can pull it out from between the top of the dash, and the row of buttons along the top of the trim piece.
9) With the trim piece out, the HVAC controller is held in by 2 screws at the top corners. Unscrew them, and the module pulls straight out.
10) The module has a big connector on each side. Pull them by lifting the tab on the connectors that is towards the front of the module. Done.
To reinstall, just reverse the procedure.
Couple of notes...
A) The first time you do this is a pain but once you get the hang of it, it's no big deal.
B) Be very careful with the trim pieces. They are a laminated sandwich of several layers of aluminum, plywood, veneer, and lacquer. The piece itself is very strong, but the edges chip very easily. Also, be careful when flexing them, especially the thin edges between the sides of the console and the radio & HVAC module. It is possible (very possible) to flex them enough to introduce hairline cracks in the surface lacquer well before you do any damage to the trim itself. If that happens, you have 3 choices...live with it, buy a new one and hope you don't crack it again putting it in, or sand it all the way down to the veneer, re-lacquer it, and then hope you don't crack it when you put it back in.