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#1
10-17-2003, 01:33 AM
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W116 climate control
HI
I was trying to figure out the C/C system on the 300SD, If anyone has any leads I would be greatful Here's the scoop, No buttons seem to work anything ,fuses are new, there is power(voltage), going to the back of the switch panel, def seems to pressurize the flipper in the dash, but that is it, I hooked up 12v just to the blower and it started to blow ? Also sometimes the car will not turn off if started and turned off qiuckly, but if revved up for a few seconds it shuts off and the tach seems to work on and off randomly? Are these things connected in some way or certain part , If the main vacuum pump on the engine is not pumping enough air will this make the C/C system not work , I know it will make the engine not shut off thanks in advance Dave 86 190E 2.3 16v -smoke 86 190E 2.3 16v -charcoal 80 300SD 69 911 Iroc replica 
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#2
10-17-2003, 09:41 AM
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I can't help you directly, but there is information here in the archives. Search for "ACC" or "climate control servo".
__________________
Rick Miley 2014 Tesla Model S 2018 Tesla Model 3 2017 Nissan LEAF Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro Chain Elongation References
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#3
10-17-2003, 07:05 PM
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Dave,
Yes, low vacuum will make the CC system inoperative since it as mostly vacuum comtrolled. Vacuum will not affect the tachometer, its all electric. P E H
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#4
10-17-2003, 07:38 PM
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Look for leaks in the vac system, and check to make sure the pump is working OK.
No or very low vac on the W116 CC will even keep the fan from running, there is a relay behind the glove box. Sounds to me like either a dead vac pump or a bad main hose. Peter
__________________
1972 220D ?? miles 1988 300E 200,012 1987 300D Turbo killed 9/25/07, 275,000 miles 1985 Volvo 740 GLE Turobodiesel 218,000 1972 280 SE 4.5 165, 000 - It runs!
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#5
10-17-2003, 08:08 PM
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Your engine shutoff issue is vacuum-related too...a vacuum-operated unit on the fuel pump cuts off the fuel flow, so if there's a vacuum leak, it will not operate properly. Neither will your ACC, or your locks. It can be a HUGE pain in the a$$ tracking down the leaks, but most of the parts to repair the leaks are not that expensive. It's NOT common for the vacuum pumps to go bad, but it does happen. Sometimes a simple diaphragm replacement will cure it, but it's more likely that you have leaks in the locking system, the shutoff unit on the fuel pump, or possibly in the climate control stuff behind the dash (a REAL bi+ch to get to!).
The notorious SERVO can also be part of the problem. They commonly go out on 116/123 cars from that era...I had to replace mine a couple of years ago. They are NOT cheap, unfortunately, but it's the "brains" of the whole climate control system. In case you don't know, it's the big thing in the passenger side of the engine compartment, up near the dash...lots of vacuum lines coming out the back, and a couple of heater hoses going in and out of it. Look for leaks, cracks in the round cylinder-like part of it, etc...Also, to compound the issue, when the servo goes out, it often takes the climate control relay (behind the glove box, inside the dash), and the pushbutton unit with it, because of a short circuit condition.  If you're not experienced, or at least comfortable with the trial and error nature of diagnosing this beast, you might want to take it somewhere. If very complicated for a first-timer, especially with no repair manual or anything to refer to. Ask me how I know!....  Do a search on "ACC" or "servo", or "automatic climate control"...there is a lot of helpful information in many of the old posts concerning this stuff. 99% of the time, the tachometer problem is due to a bad tach amp...it's the little black round thing mounted on the driver's side wheel tub in the engine compartment, with some wires coming out of the bottom of it. Do a search on "cigarette butt trick" here on the forum for a possible quick fix. If that doesn't work, you need a new one. Mike
__________________
_____ 1979 300 SD 350,000 miles _____ 1982 300D-gone---sold to a buddy _____ 1985 300TD 270,000 miles _____ 1994 E320 not my favorite, but the wife wanted it www.myspace.com/mikemover www.myspace.com/openskystudio www.myspace.com/speedxband www.myspace.com/openskyseparators www.myspace.com/doubledrivemusic Last edited by mikemover; 10-17-2003 at 08:13 PM.
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#6
10-17-2003, 08:33 PM
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Ok folks, I took the whole dash apart, The main vacuum lines going to the C/C panel where off, I plugged them back in
The C/C systems only works if I rev up the car, then all the buttons seem to work the fan but will not open or close the differnt level flaps , Also there was a kink in the tube that shuts the engine off . I pulled on it and it came out of the fire wall This line is hooked to the key switch right? I am figuring the system is not holding vaccuum and will have to trace it will a vacuum tool. The black box servo is clicking , thats a good sign i think , thanks
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#7
10-17-2003, 08:56 PM
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Sounds like you're off to a good start!
Mike
__________________
_____ 1979 300 SD 350,000 miles _____ 1982 300D-gone---sold to a buddy _____ 1985 300TD 270,000 miles _____ 1994 E320 not my favorite, but the wife wanted it www.myspace.com/mikemover www.myspace.com/openskystudio www.myspace.com/speedxband www.myspace.com/openskyseparators www.myspace.com/doubledrivemusic
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