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  #1  
Old 01-07-2018, 12:13 PM
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How to take apart W108 dash, repair vent box

I am going to tackle the job of repairing my vent box on my 71 280 SE. The control that directs the air to either the foot well or windshield isn't functioning as air is just flowing to both. I am going to enlist the aid of a highly capable amateur friend as I am only lightly capable, but neither of use has any experience with this job. Does anyone know of instructions for this job or any advise would be quite welcome. Becasue the parts are old and some are brittle I want to make sure I take things apart in the right order.
Thanks
Brad

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  #2  
Old 01-07-2018, 02:00 PM
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Take out the glove box, and for extra light, remove the speaker on top (or the blank). Once you peer inside, you will see where the cables go to, and from that point, you can try to move the levers that the wires go to (with the aid of some lube, of course).

Might be a good idea to remove the glove box door, for more "elbow room". If you need to, remove the ashtray, for better viewing.
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  #3  
Old 01-07-2018, 09:40 PM
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I've been able to observe the cables moving levers but the air flow doesn't change. Seems that the flaps or diverters are either not moving or are warped.
Thanks Larry
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  #4  
Old 01-07-2018, 09:47 PM
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Also, any foam used as a barrier/ seal in the system has likely turned to dust. Keep us posted.
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  #5  
Old 01-09-2018, 10:54 AM
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Quote:
Originally Posted by JMela View Post
Also, any foam used as a barrier/ seal in the system has likely turned to dust. Keep us posted.
Are there any "how tos" you are aware of?
Thanks
Brad
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  #6  
Old 01-09-2018, 01:13 PM
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This is a tight job. Removing the dash is not possible since it is solid steel and is welded into place. It is almost a structural member of the frame.

The heating system can be removed but this is also a time consuming task. A popular saying about this is Mercedes built a heating system and then built a car around it. And if you remove the system this is what it will seen like they did.

The first thing to look at on a 108 is: Are the cables really moving? Removing the glove box is a must but that will allow you to remove the chrome face the heater levers go through. First you have to pull out the levers and then remove the face which is held in place by two nuts on the back side of the dash. You can reach one with the glove box out and the other by going up behind the A/C housing. And if you can't get your hand back there you might have to remove the A/C unit from under the dash.

This is really not that hard, just a few screws hold it in there. And you don't have to 'remove it'; you just let it drop down until you can reach that nut on the chrome heater lever face.

Once the face is out you can see the top of the healer lever assembly. This can be removed if you have a lot of time. And there are cables hooked up not only to the top, which you can now see, but also the bottom which you can't.

One thing that is easy to do before you start is to search Evil Bay for the chrome face and the heater control assembly. You don't need to buy new ones but by looking at the photos that sellers have placed you will be able to get a better grip on just what you are dealing with. I have found these multiple angle shots to be more helpful than the photos in the factory manual since the manual only shows one view of a part.

One thing that is true regardless of what your problem is: Take you time and don't rush. All of the components are expensive.

And if you have to remove the heater control assembly then take the time to oil it all up so everything moves easily. One problem these have is they were lubed at the factory and the lube dries out. This makes them difficult to move.

And: There is a small pin in the electrical switch of the control assembly. Don't lose this pin!

Good luck.
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  #7  
Old 01-09-2018, 01:43 PM
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Quote:
Originally Posted by bracurrie View Post
Are there any "how tos" you are aware of?
Thanks
Brad
Negative - which isn't to say they're not online, someplace.
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  #8  
Old 01-09-2018, 10:37 PM
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I think I went through the empty speaker hole, to get to the left nut holding the face plate on. Lucky for me, they weren't really tight.
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  #9  
Old 01-09-2018, 10:58 PM
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This is the procedure to remove the heater core. If you you do remove the heater box then take the heater core to a radiator shop and have them preform a leak test. Make sure it is prefect. Better safe than sorry.


I just did this last week. It only took me five hours. You will need to take your time with the process of removal and installation. Many of the parts may break. First order a new heater blower fan(replace it now instead of later) and rubber seals for the heater core valves.
1. remove the vent on the dash - two screws
2. remove the left and right covers, which cover the frame between the windshield and door - just pull them out
3. remove the wood dash bow - two screws in the middle under the vent on the dash (be careful not to break it.
4. remove the dash cap - four screws which are close to the defroster vents and then pull the cap off ( it is attached at the front with clips.
5. remove the main a/c vent - unplug the electrical connection on the right side. There are about six screw on the underside it. It should pull right off from the clips which attach it to the dash.
6. remove the a/c blower - two screws on each side
7. remove the evaporator - three bolts, one on the left side against the firewall. The other two are on the inside of the compartment behind the right wheel were the antenna is. Unscrew the a/c lines under the hood. it takes a lot of effort too get it out.
*The lower heater vents will need to come out. To get to them the center carpet has to come out.
8. Remove the center consul - three screws, two in the middle and one at the front also disconnect the window switches.
9.remove the center carpet and the carpet on the left and right side.
10. unscrew the vents which are of the floor - two screws each.
11. remove the vents which connect to the bottom of the heater box - one screw each.
12. remove the glove box door.
13. remove the glove box interior - two screws and about seven clips. Unclip the light and then pull out the interior box.
14. remove the ash tray front
15. unscrew the four screws which hold the ash tray holder. One of which is the switch four the glove box light.
16. remove the radio
17. pull out the instrument cluster - there is a plastic nut which holds the cluster in. To get to it you will need to reach up from under the dash (this is easier said than done). With the nut off carefully pull the cluster out. Disconnect the speedometer cable, oil pressure line, electrical plug and the shifter indicator (this disconnects close to the steering column under the dash. Move the shifter and you should see the linkage move back and forth). the temperature cable cannot be disconnected. I just rotated the cluster and taped it to the left side of the dash. *be careful not to scratch the wood on the dash with the back of the cluster.*
18. remove the heater controls (this is a pain in the ass). There are two 10mm nuts on each side which hold the heater control face plate on. Unclip each cable connection (label them), two of which require a screw drive from the top (through the controls) and the bottom. Don't lose the clips. They like to pop out and vanish into the black hole of the dash. There are also two electrical plugs on each side of the controls.
19. remove the a/c hose - this hose runs from the far left vent down to the left side of the main a/c vent. It is the hose which right behind the instrument cluster. Be careful it likes to break.
20. remove the three defroster vents - the left and right ones are secured with clips which are on top of the dash. Unscrew from the dash and then remove clips from the vent. The right vent will fall out but the left vent will just moved to the side (watch for the small hose at the left of it.). The center vent is removed by a single screw at the center of the dash under the dash vent.
21. drain the cooling fluid from the radiator.
22. disconnect the heater core hose connections - inside of the engine compartment on each side of engine.
23. unscrew the heater box - two 10mm nuts on each of the box at the fire wall.
24. disconnect the electrical plug from the heater box - it is right next to the valves on the right side.
25. there is a bolt which attaches the box to the dash - it is on top at the front of the box. There may also be a connection at the lower front of the box.
Now you can remove the heater box. First pull the box back to get the heater core pipes out of the holes in the firewall. Then slide the box to the right. It takes a lot of finesse. Rotating the right side up while at the same time pushing to the right (this will help in getting the heater blower fan to clear the top of the dash. Go slow and be patient. It will come out.
This list may appear overwhelming but it works. The order od operations works well too.
If I missed something let me know.
Good Luck
Twinoakchef
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  #10  
Old 01-10-2018, 04:13 PM
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Yes, ... you did miss something!

You missed that you have to have the patience of a Saint!

(great write up!)
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  #11  
Old 01-10-2018, 05:59 PM
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Originally Posted by Larry Delor View Post
Yes, ... you did miss something!

You missed that you have to have the patience of a Saint!

(great write up!)
Oops... then maybe this project is not for me. After all I am an instant gratification maven.
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  #12  
Old 01-11-2018, 10:18 AM
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I had to replace the crappy USA mandated "break away" heater control levers that, indeed, did break away due to age. My solution: I called Cris, my "half-my-age" 35 year old mechanic. Painless!
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  #13  
Old 01-11-2018, 05:08 PM
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Originally Posted by Larry Delor View Post
I think I went through the empty speaker hole, to get to the left nut holding the face plate on. Lucky for me, they weren't really tight.
I noticed the same thing about the nuts holding each of these I have removed. They are only slightly firmer than finger tight but they don't take a lot of effort to remove.

Perhaps the guy that installed then no the assembly line just had enough strength in his hand that no further tools were needed.
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  #14  
Old 01-11-2018, 05:11 PM
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On #25 above...

The fan mentioned is the heater fan. The A/C fan on the 108's, unless it is an early 1967 108 with 'factory' aftermarket A/C, is located in the passenger kick panel.
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  #15  
Old 04-11-2018, 12:34 PM
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Heater Box Rebuild

I just did this on my 280sel 4.5. I took the advice of another Pelican member and had the heater core re-cored, put in a new NOS heater fan ($$$), lubed and "tuned-up" the flaps and cables, rebuilt the heater valves, and rebuilt the all of the heater controls. Now waiting for wood to be returned from Madera.
My 280 was a Phoenix/Vegas car and a lot of the parts in the dash were "cooked and brittle". Luckily I had a parts car for some of the needed parts.
You will likely break, drop (lose) a few parts doing this job. Let me know if you need any parts for you heater box,. switches, etc. I'll send them your way.

Pat
510-579-1887


Last edited by p.smitty; 04-12-2018 at 12:51 AM.
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