Re: P.M. alternator

Posted by DavidPackard On 2017/4/25 22:26:07

Hi Howard

I'll get back with you on whether the blower is running at 'normal' speed. With a sample size of one that will be quite subjective.

I don't know any of the details of my AC installation. Clearly southern California is filled with folks that could rewind an existing blower motor to 6 volts. I'm led to believe the polarity change will result in a motor that rotates in the opposite direction. The fan will lose some flow at constant speed that could be recovered with a slight bump in motor speed . . . assuming you can tolerate the current increase. All of that activity could have been done 'in-house' at CAS.

Every so often the subject of the compressor clutch will come-up at the Saturday evening car show. We are equally at a loss as to whether this is truly a 6 volt item or a 12 volt unit operating at essentially below the recommended minimum voltage. If I can find some coil resistance data I can measure mine and put this to rest. Clearly the AC would be activated after the engine is running and if the voltage regulator was less than full normal operating temperature the voltage would be biased high. My car, once started, will have a system voltage of 7.5-7.6 volts until the regulator warms . . . then it's in the 7.1-7.2 volt range.

There is also the issue of 'pull-in' versus 'hold' voltage. A half volt between the two would make a world of difference.

My unit is mounted hanging off the lip at the bottom of the dash. The 'far end' of the evaporator is essentially resting on the transmission hump. I have not disassembled to view the configuration of the motor, but I would expect a double shaft design . . . AC designs like to have lots of exit velocity and noise as surrogates for performance.

I've got a pretty good sized rheostat, perhaps I could map the clutch performance envelope of pull-in and release voltage levels. It's hard to measure the release voltage with only the unit's ON/OFF switch.

I have been toying with the idea of having an 'on-board' converter on my '54 with some type of current limiter so I can re-charge the 'constant loss' 12 volt system if the voltage gets on the low side. The two six volt Optima batteries combine to a lot of hours of running the radio. Right now I trickle charge once every three weeks.

Have you made a decision on whether your system will have a common ground?

dp