time to get the soldering iron out....my AC weirds out on me and switches to the DEFROST vents; turn off ACC for 5 seconds; turn back on....and vents switch from DEFROST to DASH. Weird. Glad you guys have already gone thru this ahead of me....would drive me crazy.

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daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
No longer selling Cluster Needles Paint
No longer selling New Old Stock (NOS) parts

Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more

I posted in the parts section two used ones that I was trying to solder if anyone wants to buy them to play with or for cores.

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Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.

Mine was doing this and I replaced the ignition switch to clear up strange problems like dash inicators coming on at odd times. Looks like it cleared up my weird acting CCU also.

My theory (open to comment and revision) is the ignition on position supplies current to the CCU. If this was interupted by sporadic shorts in the ignition switch, the CCU would be getting current on and current off signals causing it to be confused.

Plausible?
Charles

I have a few extras that I was going to resolder, but I bought a rebuild programma one. I have the extras on ebay, item # 220235685135

So you guys can play with them. $0.99 start bid, ends this weekend to be fair to everyone that cant log on during the business day.

I drive a 1989 300sel (126? )

OK i need some help this is driving me crazy, the climate control seems to have a mind of its own, it seems unwilling to change what its doing. IE Ive had air conditioning running now for 5 weeks, before that i could only get the heater running.

so far i have not tried that much all i have done its pulled the climate control module out and done a blanket resoilder of the hole board (part number 1268300885)

It used to be that you could get the climate control to change by switching the climate control off when the motor was running. then turning off the motor, changing all the setting then starting the motor again but that no longer seems to help

sometimes when i start the car it seems to think about putting the heater on (you know how it seems to like blowing air at your feet when its heating and blowing air at your face when its cooling.....) but then it stops for a second and then i think it starts the compressor, i can hear the load on the motor

as a test i disconnected the mono valve and now i think i have the air con running and the heater at the same time (the temp wheel is set to max heat)

oh most of the system is working i can adjust the fans and i can put demisters on and i can turn it off the only thing I'm having problems with is temperature. the temp wheel seems to do nothing




now the things i think it could be after reading all of your posts

1/ ignition switch -seems very odd and i think mine has been replaced all ready but did they stuff it up some how?

2/ The push button climate control module its self - even though i have resoldered all the joints i still wonder about that Potentiometer (the temperature wheel) maybe its intermittent ?

3/ the device that senses the temperature in the car - think this is the most likely culprit but don't know were its located any one know ?


is there anything i could have missed ? thanks for any help

I believe your car has several differences from the original W126's so you will need a little different information and schematic. I believe this may be a procedure to help you diagnose your particular vintage: ac still not working after ac conversion 87 300SDL

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Sam

84 300SD 350K+ miles ( Blue Belle )

thanks for your quick reply. I think that link is mostly to do with problems with the air conditioning not working at all and I don't know if it will help work out what system my car has. but I can all ways check every thing on that list

this is a picture of my push-button control unit

Attached Thumbnails

 

I believe the temperature controller is located above the passenger footwell. Do you have a copy of the factory service manual or more specifically, the schematic for your car? IIRC, yours has a small sampling fan that draws air across the sensor for better response to temp. changes. Also, the pushbutton controller was changed in 85 or 86 to a new version.

Another note, have you checked the fuses? The aluminum ones are notorious for causing intermittent problems. Use the copper ones if you can find them.

You might find someone in the Tech Help section of the forum that is more familiar with the nuances of the later 126 series climate controllers.

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Sam

84 300SD 350K+ miles ( Blue Belle )

My '81 300SD climate control isn't working and I've checked the fuse and blower motor and replaced the control unit with a questionable one. It worked for a short period then stopped. Winter is coming to Iowa so I thought I'd try resoldering the board but couldn't load the DIY page. Could someone send it to me? Thanks a lot.

Describe "isn't working". Typically, resoldering is for symptoms of no mode change, ie. defrost only. If you just aren't getting heat then the usual culprit is the monovalve.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Hi
could this also apply for the cliamte control panel of W116 , 300SD ? I also only have warm defrost and no other knobs are working. Can not regulate heat either.

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T-Bird Rules if itīs a bike...Mercedes headlight...makes it legal here...

I believe the W116 is different, and I'm not sure about the Euro model, as they have the servo. If you do an advanced search for "servo" here on the forum, you should be able to find more information. Especially check the DIY section articles that come up in your search results.

(Advanced search is found under search on the header bar at the top.)

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Sam

84 300SD 350K+ miles ( Blue Belle )

Thanks, Iīll search. Itīs a US model returned to Europe.

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T-Bird Rules if itīs a bike...Mercedes headlight...makes it legal here...

Ok I have run into one of the problems you describe in here.

Does anyone have some pictures or something that can guide me on my way, to find this foam hose, so I can figure out if it has been crushed?

It should be said, that my car is a 1987 300 E Euro model, with a manual dual zone system. One for the drivers side, and one for the passengers side.

Thx.

Never mind, found it and it seems to work fine.

There is suction, it is not a whole lot, but it is there.

But that just leaves me even more baffled, but now it is time to do some measurements on it, to see if actually works.