Packard Forum Index » Post-War (1946-54)

As some may remember, we have been discussing the Sanden clutch operating at 6v adnauseum.

Some have said the clutch will work on 6v. This may be true but I have yet to confirm it directly. Dwight H. says his 54 runs one with no issues. Another who is supposed to be running one on 6v in a prewar Clipper did not respond to my email asking for info. Others have been reported as running them but no confirmations as to who they are or if any issues.

Have been playing around and testing possibilities for my 47 AC. I can confirm clutch will not pull in at 6.3v but will at a slightly higher voltage. My thinking -- until proven otherwise -- is that those cars running them on 6v are relying on the higher generator charging voltage to do the work.

After a fair amount of testing, I am becoming comfortable at running the blower on 6v. Worst case, with the proper evaporator configuration that 12v motor could be changed out. The clutch has still been a maybe. For want of something better, I made a module to switch a small extra battery in series with the regular battery to provide a proper 12v for operation of the clutch. Have been doing testing for several days on the bench and it seems to be functioning as planned. The circuit keeps the extra battery in parallel when not needed so it stays charging. When the thermostat calls for clutch operation, a relay changes to series output and supplies the clutch only with 12v. When thermostat cycles clutch off, battery reverts to parallel again.

A second relay was added to disconnect the circuit when engine was starting so excess current is not pulled from the small battery. The resistor is to keep the charging current to the small battery fairly low. Not shown on the schematic is a control relay. If the AC power is taken from that point directly off the main battery, a relay or some means of controlling AC with ign switch would be needed.

Testing mode used the regular car battery as one battery with a charger substituting for the generator circuit. The extra battery is a small 12ah unit. Since the clutch only draws about 2.75 amps at 12v, the small battery would keep it operating for 2 or 3 hours. With the AC cycle down time going back to a charge configuration, am hoping it will work as envisioned for a considerable period of time.

Only downside I see at the moment is the absent minded mechanic hooking the regular battery up backwards. Hopefully putting the large fuse where it is will prevent too much excitement. The small fuse is just to protect the clutch and wiring.

Anyway, for anyone interested here is the circuit. It will be some time before my car is ready for a real test. I will be installing it eventually but if anyone wants to shoot the theory full of holes or even give it a try, be my guest. Any questions or anything not clear as mud, feel free.

Module will be in an enclosure and battery is in a separate package. Both are reasonably small so can be mounted out of sight and/or separated. I wanted flexibility so went a little fancy with sockets and terminal strips but all could be done wire to wire.

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Hmmmmmm. But the ground of the pump is attwmpting to feed 12 v back into the ground of battery one?????
Cheque the voltage betwwen ground and pos post of battery one.

Not sure this will work but maybw worth a try:

Starting fresh:
Dirrect connect neg post of bat 1 to pos post of bat 2 with a diode in the wire.
Neg post of bat 2 direct to clutch. Isolate ground of clutch from rest of car.
Ground clutch back to BOTH batteries with 2 seperate wires.

NOTE.
Testing your current set up:
Disconnect ground of bat one from frame of car. Place voltmeter between pos post of bay 1 and framme of car. BE SURE TO NOT USE THE ACTUAL CLUTCH FOR THIS TEST. SUBSTITUTE A 12v lite bulb for the.clutch. i say this because im not sure if the voltmeter will carry the amperage of the clutch thus damaging volt meter.

Im guessing with the above test u will find 12v going back into bat 1 from the clutch ( bulb in test case).

Not following what you are saying with the ground of the pump feeding back into ground of bat 1. There is a normally open relay contact in the path unless the relay closes for clutch to be energized. Once relay energizes the batteries are in series. Works as drawn on the bench. Only difference between test bench and on car is I'm using a solid wire for ground instead of a frame.

I am using the reg clutch and the current draw when clutch is energized is about 2.75amp.

Ok. But what is voltage reading at the ground post of bat one?!?

12v must be coming OUT of the clutch. Only placce the 12v can go from there is back to bat 1 thru the ground strap of bat 1. No????

Quote:
Correct but it's ground or in this application we'll call it 0 volts. 2 batteries in series will give 12v to the clutch coil feed wire but the return is the same potential as the battery 1 ground.

As long as the AC clutch is the only thing to see 12v, no other component will be affected and is no different than any other power supply setup with multiple voltages and polarities sharing a common return or ground in this case.

In this setup the only thing that sees a slightly different voltage is the + terminal of bat 2 when they are in parallel. Because of the resistor it is about 200-300mv less than bat 1 + terminal.

Howard - Jim Hollingsworth showed me his '40 One-Sixty Club Sedan with AC. He was operating the Saden compressor's clutch with a 12-volt battery back in the trunk. He said it would provide power for weeks' worth of usage. Not convenient, but workable. I guess you could use an 8-volt batter, but it would probably be more expensive than a 12-volt. Maybe a small motorcycle battery could serve as a power source? I know all of this has been discussed many times before.

David Flack may have a phone number for the guy from Salado who has Jim's '41 AC Clipper.

(o{}o)

Edit: Not an engineer (far from it), but looks like a nice engineering solution, lots of thought and knowledge went into it. Thanks for sharing.

Thanks, John. I guess the fellow with the 41 Clipper doesn't like email or else doesn't like the fact I'm doing strange things to a Packard. I had asked about the clutch and also asked about how the return air was done in the Clipper. Maybe shouldn't have told him my reason for asking.

Another poster is making me a false trunk AC evaporator enclosure so it will at least look somewhat like Packard might have done. He says the AC units were essentially the same in conventional and Clipper bodies. Had to reconfigure my modern AC unit to fit the space. Rather than change anything on the car to make a factory bottom duct piece fit for return air, have made a thin sheet metal plenum to go behind the rear seat to fit needs of my modern unit. Will pull air from the package shelf area and from under seat. It spaces the seat back out 3/4 inch but is barely noticeable. It looks as if the seat bottom can stay in original spot but can move out if it later proves to need to.

Am reasonably convinced this battery setup will work as drawn so until proven otherwise will go with it. Was going to mount things in trunk with AC unit. Now am planning to mount it in the real estate that became open when others confirmed nothing was there except a loom. Painted black, it will be relatively unobtrusive. More importantly, will be close to other wiring needed for relay signals.

Being lazy at heart, have also decided to give the purists something else to be upset about. Didn't want to lift the hood to find a disconnect switch so made this one operational from inside the car similar to what I did on the 56. Also works from under the hood as well. Couldn't figure a good way or place to mount the switch directly to the firewall for rotary operation like the 56 was done so made it push pull instead. Ran the pull cable thru an existing grommet and made a bracket to fit between the emerg brake and hood release. With a different Packard styled and correct knob it will be relatively unobtrusive and out of the way.

Here's a few photos of the planned battery location and the disconnect.

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