No rattles in the dash and cold cold air ever since I did the work two months ago, and that’s even during one of the hottest summers we've had in a while.
I'd definitely recommend this project as a diy.
I did this job several months ago, so the whole thing is from memory, but I think I got it pretty close. Anyway, it should be a slam-dunk for anyone with some mechanical ability who can fill in the dots with pictures and my article.
If anyone's interested email me.
1. Take note of lights out on your dash and order the appropriate ones.
2. Telescope your steering wheel all the way out and all the way down, you’ll need the clearance for later on.
3. Disconnect the battery, obvious, obvious, I know.
4. Start by removing the front window pillar covers. There are no screws holding these in place, just some clips that will dislodge with a little pressure.
5. Next remove the center console.
6. There are two screws under the tiny mat at the bottom of the bottom container. There is also a phone jack at the back of this container (regardless of whether you have a phone); this needs to be removed from its clip. Next remove the rectangular plastic molding from around the gear shift, this simply pulls up. Next you are ready to pull up the first piece of wood trim, just pull up with your fingers while you have the cup holder door open. This piece can withstand some pressure since all the wood molding is adhered to thick aluminum. Once up just unplug all the wiring. Probably a good point to point this out. No need to mark things, as Mercedes did a great job of making every connector different. The few that are the same are easy to figure out which side they go on due to their wire length.
7. Next remove the two screws at the front of the console near the ashtray. Now you’re ready to pull out the whole center console.
8. Next start by removing the dash itself.
9. Pull the fuse box cover on the left side of the dash off, then pull the right side off.
10. You will see screws to the right and left side vents and speaker covers that were hidden behind this piece, unscrew and pull these out, be careful, the plastic tabs that the screws went through can be brittle. The vent flaps are not connected to the black plastic tubing behind, so don’t worry about this breaking.
11. Now you will need to unscrew the light switch/fuse panel. This is all one piece. Just undo the few screws on the left side of the dash and push this piece back into the dash. You will not need to unhook this any further.
12. Next, pull out the black plastic tubing. These just fit inside each other and are not connected to anything. They are also very flexible, so don’t worry about breaking, or bending them as you wrestle to get them out of the dash.
13. Now it’s instrument cluster time, it sounds really scary to pull this out, but there was nothing to it. Just reach into the driver’s side vent and push out. This may be a good job for small children to do since there isn’t much room to work in there. Once the instrument cluster is pushed out, just unplug everything from the back. Again, no two plugs alike so no need to worry about putting things back wrong. It’s a good point to point this out. Before you ever disconnect the battery, while at night, figure out which lights are burnt out. There are bunches of lights in the back of the instrument cluster and it’s a perfect time to replace the 3 dollar bulbs.
14. Next remove the glove box. This is a pain to pull out, it’s just wedged in the dash and seems like it will bust at any moment while pulling it out, but thank god mine never did, hopefully yours won’t either. There are two screws at the top, and two at the bottom, the bottom are covered with rubber covers that can be pried up with a small flat head. Once up pull straight out, firmly but carefully. No need to remove the glove compartment door unless you feel you might break it in the process of removal. Once out, unplug the glove compartment light wire.
15. You’ll notice a black plastic canister looking thing towards the top of the empty hole where your glove compartment just was. This is the drivers’ side airbag, as you may very well have guessed. There are two white nylon straps that go around the back of this, with two bolts holding it to the brace bar that the air bag is also connected to. All-be-it void of any sort of Mercedes warrantee, I’m sure, unbolt the two bolts. These nylon straps hold the dash back from exploding in the face in the event of a wreck.
16. Next move on to the center of the dash. Start at the bottom and slide out the ash tray, then the sunglass holder/spare compartment. There are no screws these just slide out. It will take a bit of work but jiggle them around until they come out.
17. Move up to the radio. You will need a special tool to remove this and the environmental controls. I fashioned mine out of the top of a can, cutting a strip of steel 2” by ¼” and tapering the end to one side. Push this piece of steel into the tiny slot on the left then right of the radio. Have the tapered side pointing towards the center of the dash. This will release the clips that hold the radio to the dash. It takes some work with a fashioned tool, although if you plan ahead you can buy one off the web for a few bucks. Once the radio and climate controls are out, just disconnect everything from the back.
18. Moving on up, pull out the wood that surrounded where the radio and climate controls just were. This should just pull out (I need to check this, there may have been two or four screws holding it in place)
19. Next remove the long piece of wood trim that runs horizontally along the dash. There are no screws holding this in place. Just pull out and slide slightly to the left to remove. Next pull the tiny horizontal strip on the left side of the dash. This pulls straight out.
20. Now back to the center of the dash. There are two screws that hold the center vents in. These two screws are located just under the two vents, you must have the center wood out so you can access these two screws.
21. Next remove the passengers and drivers side kick plates. They are held in by one screw that is behind an oval shaped plastic cover in the center of the kick plate. Just use a sharp screw driver to remove this.
22. Now it’s the fun part of removing stuff under the dash. Start by removing the heater vents down there on both sides. One plastic screw that a four year old could take out and the vent slides right out. Next got to the passenger side dash and remove the nice plastic piece that hides all that scary wiring under the dash. There are a handful of screws, probably 4 that should be pretty obvious. Next remove the computer plug-in plug, and hood release. The hood release has a cable that should pull out like the break cable on the calipers of a bicycle. Remove the large plastic wiring cover that hides all that scary wiring and set aside.
23. Now remove the crash guard. You’ll see the holes, just find the right socket and extension and unbolt. There are some clips that hold it to the center part of the dash that I broke to take this out, but no squeaks after assembly and nothing seemed loose without it, so I wasn’t worried.
24. Now go to the right side and remove the plastic bottom dash cover on that side. No need to remove the crash guard, it will pull out with the whole dash.
25. Now it’s steering wheel time. Remove the plastic cowling that goes around the bottom of the steering column and set aside. Next, I did what many Mercedes owners may think is unbearable. I cut the dash. There is a small 1” piece of the dash that goes under the steering column. This piece is hidden by the plastic piece you just took off. You can either pull the steering wheel off and all things that protrude form the column, or do what I did.
26. If you made the decision to cut, unbolt the steering column. There are two bolts that hold it to the black tube brace bar that runs horizontal with the dash. There is also a bright metal brace bar that runs to another part of the brace bar. Unbolt this from the steering column. Now drop your steering column down on your seat. If you’re not scared now, you’re doing well.
27. Now work on the ignition. There are several black plastic wrings that go around the key tumbler. There is also a black wire that goes from one of these rings to a box in plain sight behind where the instrument cluster is. Go ahead and unplug this. It is the antitheft thing that detect whether you have the right chip in your key. Now pull out the plastic wrings carefully with some pressure exerted from the backside.
28. The tweeters must come out. This could have been done before, but was the first time I thought about it. Just reach up under and push up. They will remove with some pressure, then undo the wiring. This may take a small sharp screwdriver. Next thing to remove is the motion sensor in the middle of the dash towards the windshield. Again, use a small sharp screwdriver to pop this out of it’s hold and disconnect the wire. Make a mental note to fish this wire through the hole when putting the dash back. It would be easy to forget, and I don’t know what it would do to the alarm system to not have it connected.
29. Now you’re almost to dantes inferno. There are a few small bolts at the bottom of the dash and a couple around where the tweeters were, and couple on either side. The dash should be loose now.
30. You may be wondering why the dash doesn’t come out in several convenient pieces, that would cut down substantially on labor costs for this sort of repair. As best I can tell, the monolith dash keeps the dash from squeaking, less pieces, less movement.
31. Now pull, but not too hard, make sure have all the screws out. This is a good time to get someone else involved to pull the massive dash cover out. Pull up, then towards the back of the car a bit, then out the passengers side.
32. Now you would think you’re about done, but you’re only about half done because the brace bar must be unbolted and moved and the whole air handling assembly must be completely taken out of the car. I wasted hours scheming ways I could get at the evaporator and not take that thing out. It isn’t as bad as it seems.
33. In preparation for removing the brace bar, you will need to unclip, but not unplug the computer and alarm system box from the brace bar, just let them hang, or if you are worried, tie them up with some string.
34. There will be a couple screws holding the plastic container that hold the wiring harness to the air handler unit, just undo. The wiring harness is wedged between the firewall and air handler unit.
Make sure you have this held up when the air handler unit is put in. You will likely need to snap the top of the plastic container off and move the wires outside of it, just more room to work. Also, go ahead and clip any plastic tie downs holding the wiring harness, these can always be replaced, but it’s safer to have the wiring free so as not to stretch it when the brace bar is moved.
35. Next, unbolt the four bolts holding the passengers side air bag in. I choose to let the whole airbag hang by a string from the firewall rather than unplug that all-important wire. That decision was out of ignorance, there is likely nothing that would go wrong if the ignition wire was removed.
Notice in this picture I have the air bag sitting on the air handler unit with an orange ‘safety’ string attached.
36. Now unbolt the brace bar. Two bolts on the right, two bolts on the left, and three two the firewall behind where the instrument cluster once was. Move the bar down, being careful of all that wiring.
37. Now is the air handler. There are several wires going to this, although by in large, there isn’t much to disconnect here. Just find the temperature sensors and unplug. One on the front, one on the drivers side. Now, this is where I royally screwed up. A very small detail that was, for me, easy to overlook. All movements of the flaps inside the air handler are controlled by air tubes and actuators. Just leave these as is. But you will need to go to where the passengers side kick plate was and unhook the one
white tube that goes to the air diaphragm
that is just under where the passengers side crash plate used to be. Un hook this and your golden, don’t and you’ll rip it apart when the giant air handler gets removed.
38. Now simply find all those golden bolts connected to the brace bar that contrast nicely against the black air handler and remove them.
39. But don’t pull the air handler out yet, because you must first remove the windshield wiper assembly. Why you ask, because the heater core and evaporator core make attachments under that.
40. To remove the windshield wiper assembly start by removing the plastic cover that runs along the bottom of the windshield, helping to shield water away from the wiper motor and other wiring that runs beneath it. There are two pieces that are screwed down. Undo the screws then slide the pieces to the outside of the car. There are plastic clips, so you can’t just pull it straight out. Now unhook the wiper wiring and unbolt it. There are only three bolts and a plastic clip, which should be very obvious.
41. Next remove the plastic drip pan that ran beneath the wiper assembly.
42. On the passengers side you will see two hoses going into the firewall.
These go to the heater core, separate hoses for separate climate controls. On the drivers side there is one hose that comes from the heater core and two aluminum pipes that service the evaporator core.
Unclip the heater core hoses and unscrew the evaporator core pipes. You are now ready to pull the air handler unit
43. This, like the dash cover is a big piece, that will be much easier to take out with some help, although I took it out by myself. Double check to make sure nothing is connected to this. Don’t worry about all those hoses, there is really only one hose that needs to be disconnected. Now pull up and out, being extra careful not to snag any wires on your way out.
44. Once out, start undoing the torx screws at the top of the air handler.
The section that looks like a hood scoop is the part you want to take off.
45. Now you should see the devil himself. The evaporator coil is located closest to the firewall and is larger than the heater coil. Honestly it is big enough to cool a small house. Just slide the evaporator out. It was very to see on mine that it was the evaporator, dye was readily visilble towards the bottom. The evaporator can be seen outside of the air handler unit.
46. Now it’s just a matter of putting everything back together in the same order, evacuating the system and recharging it. The whole project cost me $400 with recharge.
