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There was a thread that passed through recently and I am motivated to discuss this further so I'm looking for opinions on this.

My 54 Cavalier, I bought last fall came with Add-On A/C already installed.

They made a sturdy bracket which is mounted to the right side of the engine which supports a small alternator and the A/C compressor.

A single belt wraps all of the pulleys which I don't like but it seems to work. They have an idler that rides the backside of the belt to get more wrap on the water pump pulley.

My car runs on the original 6 volt electrical system which works just fine. The A/C has its own 12 volt system which consists of the small alternator and a 12 volt motorcycle battery. The car has one of those "Gel" 6 volt batteries which only needs half of the battery bracket space and the motorcycle battery (old battery from my Harley) fits neatly to the side with a custom hold down bracket.

There is a relay near the 12 volt battery that is controlled by a switch under the dash so if the switch is off the battery is disconnected from the 12 volt system. I didn't realize the purpose of this switch until last weekend. I suspect this is their idea of how to shut off the 12 volts to the A/C system after the ignition switch is turned off.

I am going to change this so either this relay or another is controlled by the ignition switch and kills the A/C when the Ignition switch is off.

Since the under dash switch has been off (until I played with it last weekend) the 12 volt battery hasn't been charged. I believe it needs to be connected to the alternator all the time.

I had considered removing the Add-On but the temperature here in Phoenix AZ has already been over 100 so I re-considered keeping it in. I also considered moving the Evap unit to the trunk.

The under dash Evap. unit fits neatly under the Glove Drawer and you can eisily pull out the drawer.

Under the bonnet is quite neat and has a factory look. (I don't do car shows for judging). The 12 volt system barley has enough go to keep the system running at stop lights which may be due to very little contact of the belt and the alternator pulley and my mostly dead 12 volt battery.

You're thoughts please.

Jim

Since it is already had changes made to the car, and you want to keep the A/C. I would think the simplest thing to would be to convert the car to 12volts. You can always go back to 6volts later is the A/C system is not wanted anymore.

To me that is much simpler and elegant than trying to run two complete different systems on the same car. Just my

You are looking at changing out all the bulbs, and replacing the starter solenoid at the minimum. Obviously then are other things like the radio and heater fan motor that come into play with making that switch, but those aren't necessities. And you can just use the heater motor out of a 55/56 as a drop in replacement.

U mentioned a relay with a sw under the dash (all for the 12v AC). BECAUSE there is aseperate sw under the dash I assume the relay is thus a 12v relay????? It shouldn;t be. It should be a 6v relay. Then u can control the relay from the ignition sw.

Otherwise Sounds like an excellent set up to me. I'd retain the 6v system for the rest of the car. Need to scrounge NOS and NORS 6v parts for spares. Good 6v parts are becomming difficult to find.

The combo 6/12 has been done successfully and sounds like your system just needs a bit of refinement. How much depends on how much you want to do. The relay to connect things all the time would be a good step.

IMHO, changing the evaporator to the trunk may not be totally satisfactory if you are used to having a nice flow of cool air hitting you directly. Not sure if you are just planning to move and adapt what you have or get a new one designed for the trunk. On some of the newer trunk units, capacity may be an issue since you have to cool the back seat area before you feel any benefit.

The belt slip may be an issue if the alternator needs to keep output high and is under load all the time AC is on. Some installations have been done by using a two groove pulley on the compressor with the second groove driving the alternator via a separate short belt.

If you would care to post any photos of your install, am sure there would be interest in seeing how yours was done and perhaps others will have suggestions.

I subscribe to K.I.S.S (Keep It Simple Stupid). A complex system is just that.....complex. More potential points of failure. I just don't see the point in maintaining a complete 2nd separate electrical system. 6v is fine if you are trying to maintain the originatlity and all that. But with everything under the hood for the secondary 12 system already, that is really out the window. So I would think a 12v alternator (or even a later 12v generator) in place of the original generator with a simpler belt arrangement to drive all the normal car stuff and the A/C compressor, and a 12v battery on the originally location is a far more elegant solution than a rube-golderg 2-system setup under the hood.

One other thing comes to mind if you want to keep more like stock. What system do you have and what are the chances of adapting some or all to 6 volts instead of needing the dual voltage. If you have the Sanden compressor, several have running systems with the clutch working quite well on 6v (actually closer to 7.5 due to normal generator output).

The blower would be the bigger issue since there are only one or two 6v heater motor styles available. If your evaporator is a type where a mount could be devised so one or two smaller 6v motors could be installed instead of the 12v, possibly an option.

Thanks:

I'm taking this all in.

I want to keep the 6 volt system for now, one of my other hobbies is antique radio and I'm not giving up tubes yet.

I considered looking for a DC to DC converter that would cover the load of the 12 volt A/C of which the biggest part is the blower, then I could remove the 12 V alternator and the 12 volt battery.

The 6 volt system seems to have good output and I drive with the tube radio, headlights and both heaters on all the time and it kept up quite well.

If it had a good 12 volt battery it would probably work just fine but in stop-and-go the current battery won't hold a charge so the A/C slows down at red lights and has a hard time getting back up to speed.

My A/C compressor does have a second belt "V" and I like the suggestion of driving the alternator from that.

I see some of you have worked this problem out previously.

Tonight I'm driving home from work in the Packard with the air on.

Jim

I considered looking for a DC to DC converter that would cover the load of the 12 volt A/C of which the biggest part is the blower, then I could remove the 12 V alternator and the 12 volt battery.

I'd be very interested in hearing your results if you pursue this. I looked a bit last year but didn't have much luck. Didn't spend a lot of time at it either so maybe something is available. Sure would solve a lot of problems for people if something realistic that doesn't cost as much as the AC unit is out there.

One problem I ran into seems to be all the inverter companies specifically say their unit is not for use with motors -- pretty much nothing inductive for that matter. Only one I found so far that allows it is the wiper motor companion unit from Newport Engineering. When I looked into that one, the output fuse was 5 amp so not enough for AC. They currently don't list a fuse capacity but the unit looks the same as the one last year.

Another issue I found on other units is the input amps. A different company had a more than ample unit -- think it was 12 v with 30 amp max output -- a bit more than needed but again was for high power amplifiers and specifically not for motors. Even worse, specs say it would pull approx 60 amps on the 6v input to deliver the 30 out. If wired for worse case, would be a pretty substantial setup Price was also a consideration even if that one would have worked.

I'm going to poke around the DC to DC converter idea as I'm in the Broadcast Engineering Biz it seems like something I can make work.

In the mean time I'm going to try and get the 12 volt alternator system working better.

I don't know how much headroom there is in the 6 volt system. This car seems heavier duty than the old 50 Chev I drove as a kid.

I will measure the Amp draw of the 12 volt A/C first, I don't see a problem filtering the output of a DC to DC so it can work with the spike'y load of motors and clutches switching on and off. The 12 volt battery could solve that but I would like to get rid of it.

Converting the car to 12 volts seems difficult to me, besides the bulbs which are of course the easy part, you have the radio, two heater motors, the clock, antenna, starter, and generator, and ignition system.

Jim

Starter really doesn't care. Just change the solenoid. Clock will be find on 12v as it just a momentary winding pulse every 2 mins or so. Antenna would just be on turbo up and down! But that would be address with a ceramic resistor. Technically the heater motors as well.

Ignition system would pretty much stay stock except for a 12v coil and a ballast resistor.

Radio would be the only think that would require a conversion per se.