When I switched on the AC the RPM dropped to a shaky low of 500.
Not wanting to play with the idle and rack damper any more and wreck my perfect 600rpm idle I added a solenoid to the throttle linkage.
The solenoid is from a Carter carburetor for this purpose.
The solenoid coil is wired up to the AC clutch and when actuated gives the throttle a hit to add a little more RPM. After some adjustment the RPM never changes when the AC comes on.
The solenoid is mounted so it can be swung to one side for the emergency shut off.

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

Nice work.

Some VWs had a similar system... a good idea IMHO. Plus bringing the idle speed up a touch with the AC is on really helps cooling when stopped.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

A unique fix. Well done!

J.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Apprently regular Engine idle is set low for some reason.

On mine the spec is on the sticker in the Pic; looks like 700-800rpm. I suppose a worne Engine might need more.

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84 300D, 82 Volvo 244Gl Diesel

My specs say the same but at 750 RPM the idle is not very smooth. 600 is smooth in and out of gear. I think I have the best of both worlds.

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

Whats the part # of solenoid and where did you buy it?
Thanks

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1979 300D.

I have no idea of the part number but it came off a four barrel Carter carb.
The yard gave me the solenoid and kept the carb for parts. Most carbs for AC car have these I think.

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

Carter Carbs were used by GM mostly, right? Carburators were phased out in the late 70`s or 80`s as I remember, then it went to fuel injection. WOW, been a while since I have see a Carb.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Correction: The solenoid is from Rochester Carb. Four barrel Q - jet
around 1987

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

Gotta say I love having the choke in my 240Ds for this reason!

I rarely need a choke in the winter here in San Antonio, but I use it in the summer to achieve the same result when the AC engages! I can even adust the idle differently as the engine warms up!

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

Both my SD's were set to a 500-550 idle rpm. I jacked them both back up to about 750. Still doesnt help cooling much. I like this solenoid idea.

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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Idle Stop Solenoid | AutoZone.com

So which of those solenoids would work with our cars?
Those range in price from 20.00-300.00.

Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

A bracket would have to be made and can be made to accommodate any one of those.

I would use a threaded unit.

http://www.autozone.com/autozone/parts/Duralast-Idle-Stop-Solenoid/_/N-9gsoj?itemIdentifier=66230_0_0_