[TheForge] OT Anyone out there knowledgeable about automobile air conditioners and/or 12VDC motors?

[CGRAF]

Add another question.
The car AC compressor is designed to be run by the engine, which has a 
lot of power. Just how big would the electric motor need to be to 
overcome the internal resistance of the compressor?

Mike Graf

On 9/5/2012 6:39 AM, Bruce . wrote:
> I'm asking this here because of the diversity of knowledge of the
> participants in this forum.We can take this discussion off-line.
> Please respond to me directly at freemab222 at gmail.com .
>
> Did you see this:
> http://www.nypost.com/p/news/local/hizzoner_cold_feat_lYxDIMuat7x4PL7nUbdBEM
> ?
>
> Well, that just struck me as dumb -- attaching a 120VAC window A/C to
> pre-cool a car.  But then I noticed that some (or maybe ALL?) RV's
> have "window-style" 120VAC A/C's mounted on them and I got to
> wondering about it.  Of course, these RV's typically are parked at a
> 120VAC electrical hookup when not being driven, so the 120VAC A/C is
> the simplest solution.  But what about for remote use?  Say, a person
> who works out of his car in hot weather and finds he only has the
> choice of running the engine or sweltering?
>
> It seems to me that one could use the engine-driven A/C unit of a
> vehicle to cool the vehicle without running the engine.  You'd need an
> extra (12V?) motor to drive the compressor and you'd need a fan -- the
> electric radiator fan might work -- to blow air over the A/C heat
> exchanger.  You'd have to use the motor to drive the compressor.
>
> As I understand it, a car A/C already has a slip-clutch on its
> compressor pulley so that the compressor only runs when called upon to
> do so.  Maybe the motor could be mounted directly to the compressor
> shaft.  Or perhaps there's a better way, maybe involving a double
> pulley or something..
>
> Does this sound feasible?
>
> Ignore for the moment space constraints -- like where could you FIT
> the electric motor.  Also ignore power constraints -- like, how
> quickly would the electric motor driving the compressor run the
> battery down.  Those obviously are issues, but they're secondary to
> the question.
>
> Anyone?
>