[W126 Coupe] No Heat / Air Movement on Driver Side Footwell

[Dick Spellman]

Hi Elm:

Where you have an 86, you may find that the vacuum element on the face 
of the heater box or it's linkage are at fault.  Here is a snapshot from 
the MB manual.  This element looks more like a pack of cigarettes (can 
not be repaired using the G Murphy diaphragms) and has a cover just 
above it for the linkage.  The metal linkage moves from left to right 
and back.  It's this linkage that connects to the top hinges on the leg 
flaps to either side of the heater box.

Start by checking the vac element using a Mighty Vac, then disconnect 
the vac element arm from the linkage and move the linkage by hand.  You 
need to remove both driver & passenger knee bolsters to see the leg 
flaps open and close.  If the linkage is working both will move.  If one 
works and the other does not, it's the darned hinge inside the heater box.

Before buying the repair kit, you need to check the above out first as 
the heater box is a real PIA to work on and requires that the entire 
dash be lifted up.  This last bit of bad news is a big deal, believe me.

Dick



Elm Zobens wrote:

> Dick,

> Thank you for the info!

> For the life of me, I can't find any factory diagrams showing where or 

> how many flaps there are for this unit. Is there any other MB 

> documentation that speaks to these flaps, how to remove and how to repair?

> Do you happen to know the part number for this 'flap repair kit'?

> I actually need to replace my dash pad at some point anyway (cracked) 

> so I guess this may just have hastened the time line for me to do so.

>

> Just to confirm-

> Do the flaps themselves fail or the linkage connecting the flaps?

> I had already purchased the actuator repair kits a number of years ago 

> thinking that was the issue but no suck luck. Actuators hold and move 

> as they should.

> Thank you again for the info!

> Elm

>

> */Dick Spellman <spell.yy at verizon.net>/* wrote:

>

>     Hi Elm:

>

>     You will have to physically check that the one vacuum actuator

>     located on the heater box face is working the linkage that drives

>     both leg flaps.  It does sound like the actuator is moving but,

>     only controlling the passenger side.  You need to confirm this

>     first.  If the actuator is moving the metal linkage, it's likely

>     that the hinged door pivot on the driver's side has failed.  It's

>     located inside at the top of the heater box cover.

>

>     I have seen this and you have only two choices.  First remove the

>     heater box fascia (an enormous job, imho) to access the hinge at

>     the top of the box and use the MB repair kit to replace the hinge

>     and nylon gear (all one piece).  Kit is about $50 and comes with

>     numerous parts that you will not need.  The labor is at least 6

>     hours and probably many more.  I won't elaborate on the repair as

>     it's involved.  Second, is to remove the driver's side knee

>     bolster and use a pick with right angle hook to pull the door

>     closed (towards you).  Then drill out the door face and place an

>     expansion bolt affair (self made) into the hole.  I used a nylon

>     locking expansion  bolt with a nylon rod that I use to push/pull. 

>     Careful not to touch or damage the heater core and evaporator core

>     inside that flap area.  Use this extension to manually open and

>     close the door based on time of year by pushing or pulling on the

>     extension.  I set mine to just penetrate the knee bolster.

>

>     It's a whole lot of work Elm to get that box apart to repair the

>     failed hinge.  Dash cap and all must be removed.  Maybe you will

>     luck out and find that the actuator or linkage on the face of the

>     box are the problem.  The only way to know is to look at the

>     actuator and linkage as it is moved using a Mighty Vac or other

>     vacuum pump attached to the line on the actuator.  Center console

>     ashtray, radio and ACC head unit need to be removed to eyeball the

>     operation and determine what has failed.

>

>     Good luck,

>

>     Dick

>

>

>     Elm Zobens wrote:

>>     All,

>>     I have finally got my 86' SEC roadworthy again and I am just

>>     knocking out some lingering bugs.

>>     Since I've owned the car, I cannot get any air movement on the

>>     driver side footwell. It's not a big deal in the summer but now

>>     that it's getting cold, my feet are FREEZING! The passenger side

>>     is fine and toasty.

>>     I've blown out the heater core (no junk or flow issues), replaced

>>     the monovalve and verified that the circulation pump is working.

>>     The Benz documentation is somewhat vague and I can't determine if

>>     there is more than one flap that controls the floor airflow?

>>     Since there is only one vacuum actuator, I am assuming it's the

>>     same flap controlling both sides?

>>     This is driving me nuts!

>>     How can I have perfect heat and flow on the passenger side and

>>     nothing on the drivers? Everything else on the climate control

>>     and blower works as it should. All other vents and outlets work

>>     perfectly on both sides- It's just the driver side floor that has

>>     me stumped.

>>     Any tips or advice would be GREATLY appreciated!

>>     Thank you,

>>

>>     Elm

>>     1986 560 SEC

>>     2006 S500 4matic

>>     ------------------------------------------------------------------------

>>      The MB Coupes Website! W126 SEC Mailing List Postings remain property of MB Coupes, L.L.C.

>

>     The MB Coupes Website!

>     W126 SEC Mailing List

>     Postings remain property of MB Coupes, L.L.C.

>

>


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