Heater Problem

1979-1991 280SE, 300SE, 300SEL, 380SE, 380SEL, 380SEC, 420SE, 420SEL, 420SEC, 500SE, 500SEL, 500SEC, 560SEL, 560SEC
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StephenH
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Joined: Wed 27 Jan, 2016 8:01 am
Model you own: w126
Location: Gippsland

Heater Problem

Post by StephenH » Wed 21 Jun, 2017 10:55 pm

Hi everyone,
I was wondering if anyone can give me few tips on where to start with a heater problem. The heater works on the passenger side, both screen and footwell, but not on the driver's side. Just very cold air, presumably fresh air. Not so good at this time of year!
Cheers
Stephen
1989 Black 420SEL
1977 Green MGB V8 Roadster

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kimrh
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Joined: Tue 05 Jan, 2010 3:18 pm
Model you own: w126
Location: Perth WA

Re: Heater Problem

Post by kimrh » Thu 22 Jun, 2017 10:03 am

First off do you have the climatic control version with the push buttons
or the dual zone manual version with the two temp wheels for left & right side and two dials for fan speed and for airflow direction?

The auto version has just one mono valve in the false firewall and the dual zone has dual mono valves in false firewall (which control flow of hot water from the engine)
Both these versions have the same large aircon/heater box under the dash with multiple flaps for controlling airflow direction and these are operated by vacuum operated pods which open & close various flaps on the automatic version and when the pods are shot (rubber diaphragm inside splits) the pod will no longer push/pull the lever that operates the flaps thus no control of vents for air to flow out of.

The dual zone manual version the flaps are operated via the dial and levers so no pods to content with except on the main fresh air flap in the firewall to control outside air coming in-
That large fresh air flap (large flap in the firewall) is controlled by a double pod and when that fails you have no control over fresh air coming in
see pic of my dual zone manual version in my white coupe.
And a pic of LHD auto version (mirrors RHD version but everything flipped over on other side)
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87 White Euro 500SEC "ECE" 195kw
88 Black Euro 560SEC 220kw
89 Midnight Blue Euro 560SEL hydro 220kw AMG Kitted
http://www.flickr.com/photos/krh2013/sets/72157632548663623/
https://www.flickr.com/photos/krh2013/albums/72157668572599252

StephenH
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Posts: 17
Joined: Wed 27 Jan, 2016 8:01 am
Model you own: w126
Location: Gippsland

Re: Heater Problem

Post by StephenH » Thu 22 Jun, 2017 9:28 pm

Hi Kim, Thanks for a prompt reply. My 420SEL has a single wheel on the left for setting the temperature and horizontal buttons in the centre for directional control, and three vertical buttons on the right for fan control. So that sounds like the auto version with one valve for hot water control, which implies the vacuum operated pod for the flap on the drivers side is shot leading to the cold air. Hope I got that right?

Your pictures make it look very complicated but I imagine if I access everything from the right place it shouldn't be too bad. Another thought is whether a vacuum line might have become disconnected? I say this because I have recently replaced the transmission and wonder if I have accidentally knocked a line out.

Incidentally, the information / manual you provided for that work was very helpful. Not exactly representative of my transmission but very similar. As a novice I made a few mistakes but got there in the end!

Could you suggest how I make a start on the heater connections please?
Many thanks
Stephen
1989 Black 420SEL
1977 Green MGB V8 Roadster

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kimrh
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Re: Heater Problem

Post by kimrh » Fri 23 Jun, 2017 11:36 am

Quickest test is to remove both side trim carpet panels to the centre console.
Visually check the lines on the left side master strip panel - pic below.
With the car in park engine running handbrake on - you can operate the aircon control panel buttons and visually listen for any loose vac lines hissing away, as well as a visual check on the line connectors.
You may have upset a line connector in the auto trans swap maybe?
You would need to also remove both under dash carpeted trim panels (that are actually tubing for directing air to the doors) to really start digging around and checking if vent flaps are working.

Manual testing of lines/pods
First of all you need a hand held vacuum tester with a vacuum gauge attached - "mostly referred to as a brake vacuum tester" which are sold in most auto retail shops.
https://www.google.com.au/search?q=brak ... 00&bih=777
I bought mine from Repco and they are a very handy tool to have in your shed. The Mighty Vac is very popular but it is just a matter of checking around in your local auto shops.

That way you can check each vacuum line manually by pulling vacuum with the tester which will operate the pods and see if they are holding vacuum.
I have my black 1988 560SEC dash fully apart in the shed which has your same aircon set-up and can take pics to show you where all the lines run and the pods are.

Yes there is a master vacuum strip on the left side of your firewall behind the left carpet trim panel that covers the left side of the centre console - see pic below
It is just to the left of the aircon control panel - see poor quality pic of mine below
You may have dislodged one of those lines maybe - but first place to check and from that vacuum strip junction panel you can easily test all the lines to the pods after a visual check of all the lines feeding to that pod.
If you had all the trim cover panels off including the left & right under the dash and your glove box removed (which is pretty easy) you can access the two main pods that operate the main fresh air flap in the firewall on the left side and visually see if they are operating the flap by using the vac tester down at the master strip i am referred to and in the pic below.

All other pods are accessible without removing the dash - but main thing is a visual test of all the flaps/pods first before removing anything
You do not have the required permissions to view the files attached to this post.
87 White Euro 500SEC "ECE" 195kw
88 Black Euro 560SEC 220kw
89 Midnight Blue Euro 560SEL hydro 220kw AMG Kitted
http://www.flickr.com/photos/krh2013/sets/72157632548663623/
https://www.flickr.com/photos/krh2013/albums/72157668572599252

StephenH
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Posts: 17
Joined: Wed 27 Jan, 2016 8:01 am
Model you own: w126
Location: Gippsland

Re: Heater Problem

Post by StephenH » Fri 23 Jun, 2017 3:11 pm

Hi Kim,
That's brilliant, thanks. I have just had an operation on my right forefinger (damaged nerves and ligaments after slicing with roofing tin) so it will be a day or so before I can get to it, but that will be valuable thinking time.
Also, now I know where I am looking I think I might have unwittingly disconnected a line when replacing the radio recently, particularly since I had the glove box out for a DAB radio aerial.... very close to the master vacuum strip by the sounds of it.
Would it be OK to ask follow up questions once I do get to it?
Many thanks again.
Stephen
1989 Black 420SEL
1977 Green MGB V8 Roadster

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kimrh
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Re: Heater Problem

Post by kimrh » Fri 23 Jun, 2017 11:30 pm

Located a very good article on replacing the vac pods without removing the dash (same control auto control unit as yours) but this is on a LHD W126 so our RHD is a mirror image of the LHD and we don't have the the passenger airbag in the dash -instead we have the glovebox or those knee pad coin tray things they have in the US models.
The pics are very clear though which is good. Their master vacuum control strip unit is mounted on the right as ours is mounted on the left.
http://www.500eboard.com/forums/showthread.php?t=4448
87 White Euro 500SEC "ECE" 195kw
88 Black Euro 560SEC 220kw
89 Midnight Blue Euro 560SEL hydro 220kw AMG Kitted
http://www.flickr.com/photos/krh2013/sets/72157632548663623/
https://www.flickr.com/photos/krh2013/albums/72157668572599252

StephenH
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Posts: 17
Joined: Wed 27 Jan, 2016 8:01 am
Model you own: w126
Location: Gippsland

Re: Heater Problem

Post by StephenH » Sat 24 Jun, 2017 12:12 pm

That is an amazing series of posts. The guy really put a lot of work into it. I can't see the photos so I'll probably have to join the forum but if that's the type of material they have it will be well worthwhile. As I said I can absorb it before I start. Many thanks again Kim.
1989 Black 420SEL
1977 Green MGB V8 Roadster

StephenH
B Class
Posts: 17
Joined: Wed 27 Jan, 2016 8:01 am
Model you own: w126
Location: Gippsland

Re: Heater Problemt - an update

Post by StephenH » Mon 17 Jul, 2017 10:13 pm

Following on from the discussion about the heater problems and the cause probably being one of the vacuum actuators or pods, I can confirm that one of the two pods that drive the fresh air flap behind the glove box is kaput. I haven't investigated any others yet because on contacting MB parts these pods are $174 and $232! Anyway, the pods come apart quite easily and the rubber diaphragms are all that is required. Just wondering if anyone has found a diaphragm replacement kit which might be a much cheaper option. I've searched online but can't find anything. Any help would be appreciated. Thanks.
1989 Black 420SEL
1977 Green MGB V8 Roadster

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Tony From West Oz
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Re: Heater Problem

Post by Tony From West Oz » Tue 18 Jul, 2017 12:02 am

Perhaps the Forum Sponsor or members have some pods for you.
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Bartman4800
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Re: Heater Problem

Post by Bartman4800 » Tue 18 Jul, 2017 11:39 am

Are they anything like the vacuum pods to open/close the door locks?

Someone posted a "how to" in the WA MB magazine, and he used some generic bellows from fleabay.

Worked a treat and cost them something like 10 aud per bellow...


Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "missus car"
2002 VW Passat V6 30V Station Wagon (my new commuter bus)

StephenH
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Joined: Wed 27 Jan, 2016 8:01 am
Model you own: w126
Location: Gippsland

Re: Heater Problem

Post by StephenH » Tue 18 Jul, 2017 9:40 pm

Thanks for the suggestions. My mistake, those are the prices from the sponsor MB Spares. I'll look Into alternatives though and try to check out the WA mag. I think the door locks are a different shape and would probably only work with some modification. Some cheaper pods look very similar except for the metal connector, which I've discovered is removable. I also have a 'parts' 420 SEL but both pods were broken on that. So time is taking its toll. Sadly it seems unlikely there is a 'diaphragm' kit although it would make good sense. I think I just have to find the cheapest pods I can.
Thanks again,
Stephen
1989 Black 420SEL
1977 Green MGB V8 Roadster

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Bartman4800
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Joined: Fri 10 Oct, 2008 12:10 am
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Re: Heater Problem

Post by Bartman4800 » Wed 19 Jul, 2017 2:12 pm

1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "missus car"
2002 VW Passat V6 30V Station Wagon (my new commuter bus)

StephenH
B Class
Posts: 17
Joined: Wed 27 Jan, 2016 8:01 am
Model you own: w126
Location: Gippsland

Re: Heater Problem

Post by StephenH » Thu 20 Jul, 2017 11:30 am

Hi Bart, I'll have a look at those links and compare parts with the bits I have. I suspect they are very specific though. I haven't found anyone who has heard of a kit so its probably a case of finding the cheapest pods I can.
Regards
Stephen
1989 Black 420SEL
1977 Green MGB V8 Roadster

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