Continuous hot air from heater

[Mike K]

With summer approaching and the roof down, I've noticed that I'm getting a continuous blast of hot air irrespective of the lever settings on the dash.

I removed the rubber heater valve access cover on the firewall, removed the valve and checked the O-ring which was intact. What I did eventually find was that the heater control lever was dangling loosely and was not connected to the panel. With the help of a tube-camera I found that the link connecting the lever to the heater is broken at the panel; see pics below.
I've borrowed the 2nd pic from the technical manual to illustrate where the link is broken

Without stripping everything out, the only way I can think of dealing with this is to manually turn the valve to the off position for the summer and then reverse the process just before winter. Any thoughts or input are welcome....

[Jonny B]

Seems like a sensible approach. Will be curious of what other creative possibilities exist. It is indeed a major pain to get access to do the repair.

[UJJ]

You can get to that flap by removing the freh air inlet cowl outside the car in front of your windshield.
This is not a big job, however, the flap itself is not cheap. I think Gernold at SL-Tech has a few used ones.
Urban

[georgem]

The flap isn`t too hard to get out and I repaired mine with epoxy putty - now its probably stronger than new and way cheaper

[450sl]

i bought a new one...

[pdc]

Mike,

You're right, that will be the easiest to do without stripping down. Since your valve is not stuck it's an easy one to open and close the heater core valve.

[hkollan]

Hi,

A new fresh air flap is on promotion now.
According to MB Classic parts search site:

FRESH AIR FLAP
Part number   A1138300142
Price excl. VAT   €66.00

Paid quite a bit more for this piece about  5-6 years ago

Hans

[Mike K]

I've looked at removing the air inlet cowel in front of the windscreen, I really don't want to start something that I can't finish.....and have decided for now to stick with turning the valve on and off between winter and summer.

Thanks everyone for the feedback, much appreciated.

Best,

Mike

[UJJ]

It really isn't hard to do Mike. Just a few screws and the wiper arms and you are right at it.
You also can clean or replace the filter at that time, an often neglected maintenance on our cars.
Urban

[Mike K]

Curiosity got the better of me, I followed the advice here and opened up the fresh air inlet cowl and stripped everything out. This "8" shaped frame and piece of fiber was lying loosely in there.
Is this supposed to be the air filter? (see pic below).

I've closed it all up again, leaving this frame and fiber out for now. I'm most probably going to try and epoxy the lever arm back into place on the flap and see what happens....
For now I've closed the heater valve manually.

Thanks and best,

Mike

[WRe]

Hi,
yes, what you found is indeed the fresh air filter with it's "8-fastening" (MB no. A1138300118).
...WRe

Source for pictures: http://www.pagodentreff.de