Idle question: Why use vacuum?

Like the subject line says, this is an idle question, but why do auto mfrs use vacuum circuits for things like cruise control and the mix door in the cabin heating/cooling system? Particularly in the latter
case, why not just use direct mechanical actuation from the console knob to the mix door?
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Fewer parts. This is why you don't have to reboot your car... yet.
: Like the subject line says, this is an idle question, but why do auto : mfrs use vacuum circuits for things like cruise control and the mix : door in the cabin heating/cooling system? Particularly in the latter : case, why not just use direct mechanical actuation from the console : knob to the mix door?
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Tom Line
tlineN0 snipped-for-privacy@iglou.com
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snipped-for-privacy@larwe.com (Lewin A.R.W. Edwards) wrote in

Before about 1966, they did. It was a simple, foolproof system that was easy to use and repair. About the only thing that could go wrong with it was a sticky or frozen cable.
I think they changed because the vacuum system allows for quieter, fingertip operation. Moving cables took a little effort. Maybe some poor lady broke her nail or something.
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There is such a thing as electrical cruise control actuators. Check aftermarket prices, they cost more. As to why they cost more I have no idea if it's because there are less electrical ones made or they just don't want to put the design effort/cost into designing a new one. IMO electrical ones would slightly increase engine reliability due to less possibility of vacuum leaks.
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Vacuum is in plentiful amounts. The vacuum systems are very inexpensive. Vacuum provides a great deal of power. Vacuum is what gives you power brakes.You can put a vacuum motor in lots of places with out having to worry about how to route the cable or linkage and have it work with out binding. Design flexibility. Vacuum can be stored.

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Bad answer. Vacuum devices wear out. Hoses rot, as do diaphragms. If you ever get a vacuum control system needing repair, you have got a big problem.
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Cables bend and bind. The bell cranks that cables attach too break. Both cables and the parts that work it break and go out of adjustment. Cables are a pain to replace, and can not be repaired. The nylon vacuum line does not wear out, and because it is not exposes to the heat of the engine or sun light so they stay pliable. The tubes are strong, hell they are just about indestructible. If by chance some one manages to damage one, can be repaired with out major work, a kinked or broken cable can not, replace only. Electric servos go open and require electronics to control. The electronic controllers are expensive. The connections are prone to corrosion. The nylon tubes that route the vacuum are the most trouble free thing on the car. The most common problem would be the control head leaking. Easy to get at and replace. The vacuum motors out last most cars, so can be called trouble free. The vacuum system is the most easy to diagnose when something does go array. If you think that diagnosing and repairing a vacuum system as "big problem", I would say you are not all that bright. All in all, my answer is a good one. Have a nice day!

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Is that right, asshead? Wait till you've had an entire dash apart, trying to trace 3 dozen vacuum hoses.
Cables can be easily traced and easily fixed.
My first impression of you is that you are a know nothing blowhard who fancies himself some kind of auto expert. That impression continues to be reinforced.
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Read on, you'll see who is the "asshead". Little FYI, use the brain BEFORE you take stuff apart. You know, look and READ a manual? Helps to understand it as well........... Use tools? Know what is wrong first. It's not all that hard.

Last count I believe there are four to six lines depending on the model. Vacuum lines are color coded. By using a schematic you can find which line goes to which motor. Then you use this thing called a hand vacuum pump, dont have one? Suck on it. By removing the vacuum harness from the control head ( which by the way is very easy to remove ) you can test each individual line with out taking apart the whole dash. It's real simple, put the pump on the line and pull a vacuum. It holds vacuum or it does not, real simple.You are not all that bright are you?

Hell, if your taking apart the whole dash to do a diagnoses, you better be able to see and trace the cable! Better yet, if you know what you are looking for BEFORE you take it all apart to find out what is wrong you would not be trying to trace the infamous 3 dozen vacuum lines.

Really mister 3 dozen vacuum lines? Look up in a manual, tell me the average number of vacuum lines going to a automotive climate control system, then get back to us. Most manuals even tell you how it operates. With that information, you can have an idea what is wrong before you tear apart the whole dash.
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Hey "asshead", what's the problem? To complex for you? The "blowhard" unraveled your "first impression"? Let me ask you, are you a cop?

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controls work". If he knew how they worked he would know how good they really are. The thing I hate about cables is when they get old, something likes to stick and/or break and they get hard to move. I can't tell you how many heater controls I have put in the 90 and 91 Crown Vics. You know the hot/cold one that cable drives the hot/cold door. Hey donut, if you are a cop that worked patrol, chances are you drove one of those crown vics with a broken hot/cold control sometime in the past. I bet Ford made a fortune selling those damn controls :)
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This didn't become a real problem until they started using plastic sheathed cables that don't "breathe."
The old coiled metal ones not only could "breathe," they could evaporate moisture and could be lubed with spray lubricant.
Sure, the coiled metal ones could freeze if not used for a long period of time.
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Plastic or no plastic it's been the problem all along. And it does not matter the type, a bowman type cable or a twisted wire. The plastic sheath was far better though, no metal to metal contact to make rust. The plastic also acts as a lubricant.

Buy the time someone thought of lubing, it's too late. The cable sheath stops would be bent or broken. Beyond that, just how many people actually lubed them? That's why the plastic sheath is now used, it's self lubricating. It's really not an easy job, and it's messy. Many of the cables are harder to get at than vacuum lines. The cable system is just plain inferior.

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I don't think that's up to you to decide.

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"decide" just as much as you. :)
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It wasn't meant as a troll, it is I typed it. It is not for you to decide if I am "harsh" on some one or not. That's up to me to decide. Just as it is NOT up to me to decide on how YOU make a response. Or where you make your statements; top post, bottom post or in-between lines. It's not up to me to decide on if you use HTML or plain text.

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that you are too harsh for deciding to tell him he is "not to bright". I just decided to tell you that because someone doesnt understand the vacuum system doesn't always mean they "arent too bright", it just means they decided not to learn about it. Now remember, I decided to post this and I can post what I what, when I want, and where I want because I decided to, and its NOT for YOU to decide. :)
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Hmmm, I have decided this thread is silly
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R. J. Talley
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