The CC in my 82 300D doesn't work-PO managed to get a bunch of oil in the vacuum lines. If I was going to repair it I would have to replace all the vacuum stuff.

I know I can just hook up a switch to turn on the coolant pump & monovalve; but is there a way I can manually control the fan speed?

My final goal is to have the defrost, vents, and floor always open; and then slow, low, med, high fan speeds.
I've got a couple gauges I'd like to put in place of the bulky stock unit

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Try diesel mercedes yahoo groups.

for fan speed, consider a potentiometer.

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yeah, I have to say, manual control would be sort of nice. I really don't get the buttons. A pot for the fan speed would be real sweet, as opposed to the "filled in fan" and the "hollow fan" These cars are so well built, but my 1980 toy hilux pickup had better heater and ac control than my 300td. maybe when it is working perfectly, it is sweet, but it sure seems like re-engineering somethin that works reliably by having vac operated this and that for dash control. It is hard to beat a push/pull cable for reliability

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1983 300td - Velvet 265,000 mi
1975 Toyota Landcruiser FJ40 160,000 mi
2004 Toyota 4runner 103,000 mi

If I have seen farther, it is because I have stood on the shoulders of giants.
- sir isaac newton

You live in the winter rust capital of the world. Find a cancer eaten 240 in a boneyard with manual controls and swap it all in. The result will be better. RT

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When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

I may be able to strip from a 77 300D parts car. Not sure when.

if it's like my car, the fan speed is run by a resistor box which is on the right fender. in theory you should be able to use this with a 4 way switch to get 4 speeds. or a pot. or if you have the old servo crapola system, nevermind...

$318, must be real gold.....

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1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.

I think Ill match up a 5 position single throw rotary switch up to the resistor box(I've got one too)

I wonder how much current the fan draws on high? Does anyone know the resistance values of the coils?

__________________
$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

its not too hard to fix the vacuum components of the ACC, all you need is a hand held vacuum pump and replace what its needs to be replaced.

Its better to fix the system then do a hack or band aid fix because the system works fine when its hooked up properly.

The system is in place was designed by engineers not someone who figured to put any thing and not have a good system.

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

those rarely go...

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Yeah, don't kill a super-engineered system but...
I want to use the space for gauges/controls and would really prefer a system that lets me turn on the heat but no fan, or a slow fan, etc.

Also, a mityvac will be $40-ish
Plus vacuum elements($60-ish EACH)
Plus vacuum lines
Assuming my controller still works despite getting soaked in oil

__________________
$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

i hear you simple=better. It seems OVER engineered a bit.

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1983 300td - Velvet 265,000 mi
1975 Toyota Landcruiser FJ40 160,000 mi
2004 Toyota 4runner 103,000 mi

If I have seen farther, it is because I have stood on the shoulders of giants.
- sir isaac newton

If you think the w123 is over engineered then dont own a modern benz with computer controlled climate control with dual and 4 zone climate control. W123 climate control is a walk in the park compared to those systems

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

OK, for my 83 300D I opened the can of worms last year by making my own manual climate control from a control head of a 2001 Mustang I got on EBay and a cable and water valve from Old Air Products. I canned the Aux Water Pump. I tinkered with the resistor wiring and ended up with 4 speeds I can live with. I get warm air in about a mile after startup. The conversion is not for a novice but those with some electrical and auto repair experience can handle it. I had to trim the control head with a scroll saw to make it fit in the dash.

Don't get me wrong-I'm sure the system rocks in both types of car; when it's in tip top shape. This is a battle of my limited budget, and lack of urge to keep everything stock.

__________________
$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment