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

[Dick Spellman]

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

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