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Early Style HVAC I Manual Slide Controls Adjustments

17K views 24 replies 12 participants last post by  sloxl8 
#1 ·
I recently took out the dash and heater box so I took some photos of the levers and flaps and I have attached some brief comments on their operation. If I have made any errors, I won't be at all offended if you point these out so I can correct them.
 

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#3 ·
Great job! I don't want to even think about going in there!

It would be useful to know which model year cars the write-up applies to. I did not study it in detail, but one or two items seemed different from those on the very early 107s (72,73).
 
#4 ·
Year models



I can't be certain but a lot of the manual I have refers to 450SL up to Aug '81 and all RHD after that date. My lower heater box has about 6 different part numbers on it with an arrow pointing to mine. I've got the number written down and a pic somewhere- I'll look for it. My fascia is in the pic below. From what I've seen on the forum the main differences are the addition of vacuum controls and electronics on later models and ofcourse if there's no aircon it would make a difference.
The main box pieces are so flimsy it's no surprise they give trouble. Apart from the aircon evaporator and the heater core there are 5 main pieces in the heater box in my car. The base body, the flap unit (4 flaps- levers 1 and 4), the top cover, the small oval centre vent and the lower heater box. They all come apart. A detailed description of the dismantling process in in my "to do later" file
 

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#6 ·
I hope it's the levers outside the box, but from what I've experienced during recovering flaps with foam and re-installing the flaps. It could be the flaps catching inside the heater box. The flaps attached to #1 and #4 levers have no actual hinge, they sort of "hang" off the connecting rod with one of those silly push pins and the flap can easily become stuck because they are unstable.
 

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#10 ·
Actually... it is because there's plenty a heat in the middle heat levels where there is no issue with levers. Only when my wife plays with them that I have to use my sophisticated fix. ;)

But yes... a wiggle fix usually pushes any repair to the bottom of every priority list
 
#14 ·
Heres a buyer beware message for manual controls. When I bought the 75 we checked all the heater controls and levers to make sure they operated smoothly without hanging up
which they did and should have because sometime in it's life they had been disconnected from the heater box. Surprise, the flaps were jammed open.
 
#15 ·
107 ac leaks

For aussie mers

Greta photos and description on the adjustments
Im in queensland and writing in 2015
I have a74 sl, and i have resolved all the issues of the ac leaks and poor airflow, and have greta ac and no wet carpet anymore
However, i have a water ejection from the air outlet onto my feet when cornering
Their is no leak under the carpet just a gush of free water
I have installed additional drain holes in the ac/heater casing and have installed a water catch tray under the whole unit

Im told that their is a drain between the upper and lower sections that is blocked and soem water condensation is building up and unable to drain down
I have put a camera up inside and cant see the blocked drain
I cant find a unit at a wreckers to have alook at
Do you have any suggestions or diagrams or phots of where this internal drain may be?
Thanks

Jeff
 
#16 ·
For aussie mers

Greta photos and description on the adjustments
Im in queensland and writing in 2015
I have a74 sl, and i have resolved all the issues of the ac leaks and poor airflow, and have greta ac and no wet carpet anymore
However, i have a water ejection from the air outlet onto my feet when cornering
Their is no leak under the carpet just a gush of free water
I have installed additional drain holes in the ac/heater casing and have installed a water catch tray under the whole unit

Im told that their is a drain between the upper and lower sections that is blocked and soem water condensation is building up and unable to drain down
I have put a camera up inside and cant see the blocked drain
I cant find a unit at a wreckers to have alook at
Do you have any suggestions or diagrams or phots of where this internal drain may be?
Thanks

Jeff
The drain holes (they are protruding tubes -not holes) are at the bottom of the heater box. The rubber tubes that slide over them may be split or blocked or the heater box itself may be cracked. Another possible cause is a hole in the scuttle. I have a spare complete heater box I can show you if you can get to the Gold Coast. Otherwise I can send you a lot of photos of the various parts of the box. I'm assuming that yours is similar to mine. Let me know.
 
#18 ·
107 Heater lever 4

Hi,
I've had my 1988 300sl Anthracite Grey, Hong Kong import, for a few years now and it's been awaiting some attention. Just had the brakes redone they had seized and some rust areas near engine mounts fixed. Replaced harmonic balance and transmission cable that had been leaking. Took it for a spin yesterday and damn near fried my face off! Heat coming from windscreen vents and right hand lever 4 drivers side (Aussie style) won't go to full up position. I couldn't check the aircon as I was afraid I'd blow it up till I fixed this flap anyway. Although I did turn the Aircon dial and it was left on a little bit and ti made the radiator dash light up. Switched to off and didn't see this again. Although I'm suss that the whole unit may need attention. It all worked a few years ago. After seeing Aussiemercs pictures an descriptions I doubt I'm up to it! I'll climb in and try the under dash approach first. Otherwise I may be annoying and ask lots of questions or ask who the hell can help!
Thanks Aussie merc for the great pictures and descriptions. I'll try to get a pic up later of the beast.
 
#19 ·
Constant heat

Hi,
I've had my 1988 300sl Anthracite Grey, Hong Kong import, for a few years now and it's been awaiting some attention. Just had the brakes redone they had seized and some rust areas near engine mounts fixed. Replaced harmonic balance and transmission cable that had been leaking. Took it for a spin yesterday and damn near fried my face off! Heat coming from windscreen vents and right hand lever 4 drivers side (Aussie style) won't go to full up position. I couldn't check the aircon as I was afraid I'd blow it up till I fixed this flap anyway. Although I did turn the Aircon dial and it was left on a little bit and ti made the radiator dash light up. Switched to off and didn't see this again. Although I'm suss that the whole unit may need attention. It all worked a few years ago. After seeing Aussiemercs pictures an descriptions I doubt I'm up to it! I'll climb in and try the under dash approach first. Otherwise I may be annoying and ask lots of questions or ask who the hell can help!
Thanks Aussie merc for the great pictures and descriptions. I'll try to get a pic up later of the beast.
My hot water valve is default open ie constant heat if it's faulty. Not sure about yours though.
 
#21 ·
Reviving the old thread.

On 1976 450SL, when operating the levers #1 and #4, they move the upper flaps, but the lower flaps (as depicted with red arrow on the picture bellow - "AN ILLUSTRATION OF THE LEVERS AND FLAPS ON THE OLD MANUAL AIRCONDITIONING / HEATING ON W107", page 6 by Aussiemerc) are jammed (I've found wasp's nest in the gunsights, so I believe part of it fell into the heater box and caused jamming of the lower flaps).
My question is, whether it is possible to access the lower flaps in the top heater box by only removing the lower heater box.

I've also noticed that "sandpaper" on flaps is hanging off of the flaps and I wonder what material would be best to use to replace that "sandpaper". Is there any catalog number available for original "sandpaper" spare part?
 

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