'55 R-122 rehab

I blew out and pressure tested the heater core on Saturday. 13lbs for over 30min. I'll call that good. I re assembled the heater and installed it in the truck. I had to rework the old crusty shut off valve, but now I've got a good one. im running a 6v tap from my battery bank to run my gauges. That power feed runs through a relay. It took me a minute, but I was able to scrounge up a relay with double 87 contacts.]

You can likely "get away" with a center tap for very small loads like gauges with little or no ill effects, but the same DOES NOT hold true for higher loads like heater fans.
For the sake of argument, lets say the heater fan draws 5 amps @ 7.2 volts. You are charging you battery cells in series, with 12 volt (nominal, 13.8-14.2 actual) but loading the "lower" 3 cells with an additional 5 amp load. This means the "upper" 3 cells must pass 5 addional amps to replace the load on the other 3 cells, they will over charge and over heat, while the loaded cells will not fully charge. The long and short of it is you will have short battery life and risk body damage from acid expelling from overheated cells.
It is possible to make an alternator charging system that has duel (or more) outputs that are in lock-step with eachother. Delco made such an alternator for use in 24 volt start, 12 volt run trucks. The same idea can be used to make a 6 and 12 volt unit.
Best would be a 12 volt heater motor, it load the system correctly, next best would be a high amp dc to dc convertor, which places the 6 volt load across the 12 volt system. lastly and a very distant 3rd is a resistor which will not allow for varying amp draw (like motors have) to reduce the current to the motor.

I knew there would be an imbalance , but I hadn't considered that it would that drastic. I'll start exploring my options.

Jared- where did you get your 12v fan at?

Cell balance is very important, on some types of batteries (like LI ion) it can cause a thermal run-a-way, Lead acid are more forgiveing (up to a point) but some battery banks monitor each cell in a battery and cut the charge if they get out of balance to prevent damage. Lead acid will work for while, but will give short life as three cells will be chronically overcharged and three chronically undercharged.

I'm running 2 optima agm batteries currently. For now the fan won't get much use. I found a buildout for a 12v-6v converter that'll run 10amps. I'm also thinking thre fan motor size looks to be about the same as trucker aux cab fans...

When I can find the time I'll hook an ammeter to the current fan to see what it draws. I'll also put a caliper on the motor and a few cab fans I've collected recently.

12 volt motor would be best, if you have an MEI catalog or something similer, there are a whole lot of them made, 12-6 would be my 2nd choice if it has enough "surge capacity" to start a motor.

Jared- where did you get your 12v fan at?

I got it off ebay, motor only. The ad said it was for a 73-79 Scout, but I think there are plenty of other motors that would work as long as the shaft diameter and the mounting suds are the same. I think that size motor is used in a lot of other heater/blower/fan appications. Mine is a squirrel cage fan so that had to swap over to the new motor.

Here's a few links I have...
Blower motors and other heat/AC stuff.

RedDot seems to have a glitch for the catalog,all you get is the cover.
I found a vendor site with usable PDF catalogs though. Actually have done business with them back in the day,they were the "go to" place when service said we need it today. They're also a Bergstrom/Kysor dealer.

http://www.rossairworks.com/content/view/21/16/

Bergstrom
http://us.bergstrominc.com/kysor-parts

Both the above catalogs list motors with dimensions,they also have a variety of resistors,switches and just about anything else for heater/AC systems.

Not as good as above,I'll post it anyway.
ProAir
http://www.proairllc.com/parts

Here's some switch catalogs;
http://www.carlingtech.com/sites/defaul ... atalog.pdf

http://www.indakswitches.com/

http://www.lockcraftproducts.com/

FWIW, My '79 Scout had a rheostat for the AC blower motor speed,I really liked that it could be hurricane force or a faint breeze. The PN seems to be NFG, gets no hits with Google.

Scottso- thanks for catalog links. Tons of helpful info there. I should have measured the motor before I reinstalled the heater last weekend. Oh well...

I figured it would probably be wiser to have a pn for a name brand motor in hand if you try to find one at a local FLAPS,even today's "parts men" should? be able to cross it.
Since heaters were an option and aren't in the L/R books (don't know about the S) I don't have any #'s to work with.

Plus those cats. have other things people seek,like squirrel cages,control valves and even heater cores that might be adaptable.

Been ordering some parts over the last week.
2 vent windows and 2 door glasses
Weatherstripping kit
Ih voltage regulator- Thanks for the ebay tip scottso.
Amber foglights from speedway motors- had to send them back for exchange as the lenses were different shades.
'70s Mercedes dash vents
A proper delco ignition switch
Stop tail lamps w/o lic plate lenses
Another VW fan motor switch to go with the vw resistor pack I have to give me 4 fan speeds.
Starter motor brushes
Flush mount 360* swivel d-ring tie downs to mount in the bed floor
I believe I have an appropriate 12v fan motor and I hope to secure another 235/85/16 tire for a spare next week.

I was assigned to a new position in my company the other day. My wife and I will be relocating to the Minneapolis/St.Paul MN area this spring. Won't be a ton of time to work on the truck now with needing to prep our home for sale, but I'm sure I'll still manage to make some improvements along the way.