Automotive Air Conditioning Information Forum (Archives)
AC clutch
Larry in Virginia on 
Wed July 07, 2010 10:22 PM 
I am looking for a 6 volt AC compressor clutch to convert a 12 volt compressor to 6 volts. Does anybody know where I can find one?
Larry
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Larry in Fishersville
bohica2xo on Wed July 07, 2010 11:15 PM
What is the make & model of the compressor you need the clutch for?
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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Larry in Virginia on Thu July 08, 2010 12:28 AM
Any kind.
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Larry in Fishersville
bohica2xo on Thu July 08, 2010 1:08 AM
The only compressor equipped with a six volt clutch that I have actually held in my hand was a York. Now made by TCCI. You may be able to find a NOS 6 volt clutch for the York - contact the site sponsor - AMA and see if they know of any.
B.
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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Larry in Virginia on Sat July 10, 2010 4:25 PM
I also saw a York one time. It was in a 1966 VW bug, but I can't find one now.
Larry
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Larry in Fishersville
Cussboy on Sat July 10, 2010 5:53 PM
Isn't all that matters the ohms resistance?
Cussboy on Sat July 10, 2010 5:53 PM
Isn't all that matters the ohms resistance of the AC clutch coil?
Edited: Sat July 10, 2010 at 5:54 PM by Cussboy
emsvitil on Tue July 13, 2010 1:50 AM 
The magnetic field generated by a coil is a function of the amps flowing thru it and how many winds of wire is in the coil.
To get the same amps out of a 6v coil, the coil will need to have 1/2 the resistance of a 12v coil (with same amount wire winding).
To get 1/2 the resistance, the 6v coil wire would have to be a larger gauge wire that has 1/2 the resistance of the 12v wire.
To get 1/2 the resistance the wire needs to be 3 gauges larger (i.e. 22gauge/12v to 19gague/6v)
The larger gauge wire will make the coil physically larger..
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Ed
SoCal
ice-n-tropics on Tue July 13, 2010 10:50 AM
The first OEM A/C electromagnetic clutches were on the 1952 Nash Weathereye A/C (6 volt). It was a 2 cylinder "lawn mower" compressor
A typical new clutch will engage at 7.2 volts (and meet the static torque requirement) when ambient temperature and a little higher when engine underhood temperature. Therefore, there is a large factor of safety to allow for very large air gaps due to wear between friction surfaces. Higher temp windings have increased resistance and more voltage is required.
Smaller air gap between the friction surfaces require less engagement voltage.
Option 2: For the same wire gage a 6 volt clutch can have less windings.
hotrodac
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Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod
bohica2xo on Tue July 13, 2010 11:44 AM
The six volt clutches were no larger, but they did draw more current - something that is in short supply with a six volt system.
I had a 1966 VW type 3 with dealer A/C. It had a 6 volt York, along with two electric fans on the condensor. You had a choice - headlights or A/C. If you ran both, you were running a 6 amp net loss from the battery with the OEM 30 amp generator...
What sort of vehicle is this for?
B.
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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Larry in Virginia on Sat July 17, 2010 12:38 PM
A bit of electrical theory here might help clear the air and get back on track.
If a 12 volt device draws 5 amps, it will be a 60 watt load. (12 volts x 5 amps =60 watts). An equivalent 60 watt load at 6 volts will require 10 amps. (6 volts x 10 amps = 60 watts).
There are only 2 ways to do this. One is to disassemble a 12 volt coil and rewind it with fewer turns of a larger wire. The other is to get an already existing 6 volt coil and be done with it. I prefer the second method because the coils are made in a way that the first method is next to impossible.
There are 3 sources of which I am aware. Old Packard, old Nash, and old VW. Nobody at any of the salvage yards I've contacted seem so know they ever existed.. That is why I am hoping I might find my coil through this forum.
Thanks,
Larry
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Larry in Fishersville
bohica2xo on Sat July 17, 2010 2:56 PM
Ok, let's try this again.
What vehicle, and what compressor?
There are several ways to make a compressor run on a six volt system. The bigger question is why?
If this is a 100 point restoration, then sure. But a restoration would require a very specfic compressor assembly. If this is simply to A/C a daily driver VW, convert the car to 12v.
B.
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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Larry in Virginia on Sat July 17, 2010 5:47 PM
Brand and model do not matter, but for the record it's going into a 1955 GMC. I plan to replace the 12 volt clutch (or just the coil) on a new OTC unit if possible. If I can't, then I'll rebuild the old compressor and design my own mounting for it.
Larry
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Larry in Fishersville
bohica2xo on Sat July 17, 2010 6:06 PM
Ah progress.
A 1955 GMC - with the original 270 I-6? Cool.
What is the balance of the system made up of? a vintage underdash unit?
All of this does matter. A compressor should be matched to the rest of the system. If you are not looking for an authentic appearance, any compressor will do. If you want to stay with the York, that can be done too.
An MSD 8989 will run any 12v compressor clutch from 6 volts. Good for 8a max @ 12v from a 6v battery.
B.
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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Larry in Virginia on Sat July 17, 2010 8:38 PM
All I need is a 6 volt clutch! Where can I get one?
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Larry in Fishersville
Larry in Virginia on Tue July 20, 2010 8:19 PM
No lack of power here. I changed a few parts in a 67 amp alternator. It now provides 67 amps at 6 volts, positive ground.
Larry
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Larry in Fishersville
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