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I have been blogging away on add-on A/c but I must have missed this thread.

I have a separate 12 volt system in my Packard Cavalier and the 12 V alternator can't keep the 12 volt battery charged in stop & go with the A/C on.

I was thinking of trying the Evap fan on 6 volts keeping in mind my 54 is positive ground. I would keep the Sanden clutch and thermostat control on the 12 volt system which would keep up without the fan.

One question is will the fan run the proper direction on Pos ground? I don't know if the fan motor on my system is internally grounded or I get both wires. If internally grounded maybe I could flip it end to end.

Getting this out is not going to be easy which is why I waited to cooler weather.

At the moment one relay controls the 12 volt system from the Ignition Switch.

My testing verifies the Sanden 12 volt clutch will NOT engage reliably on the 6 volt system.

Jim

Quote:
The direction of the motor is a question. Typically the older one or two wire motors would run the same direction regardless of polarity because the armature/field relationship is determined internally with the brushes. A Packard heater motor is a good example of that kind. It doesn't care and generally if more than one wire, the wires are the same color. The 4 wire out 3 speed modern motor I've been playing with also doesn't care. It's direction is determined by the fixed brush and coil relationship.

The question arises with the newer permanent magnet motors. Many of the universal heater motors are permanent magnet two wire and have a red and black wire out. Those do care. The way to make them universal is just reverse the wires for direction needed. If you have one of those, then yes, polarity will be an issue.

It will be interesting to see what the rheostat or resistor speed control will do on 6v. I haven't tried a unit utilizing a rheostat so don't know how much voltage the 12v resistor will drop on the med and lower settings. If yours is that type, am anxious to hear how it does on 6v at anything other than high speed. I would verify that is the type you have though and not one of the electronic speed controls. Many of the aftermarket units today have gone fancy & I'm fairly sure those won't like 6v at all.

I would be interested in results if anyone wants to try this setup. My car is a long ways from being in a condition to give it a go so it's only bench test and theory that it will work as expected.