Definition, pumps/compressors, was A/C questions ...

[dardal@xxxxxxxxxxxxxxx]

No argument on the useful info here.  I don't want to be too picky, but in mech.
engineering terminology, a compressor is a device that "motivates" flow of a
compressible fluid (gas), whereas a pump operates an incompressible fluid. 
When R134 or R12 enters the AC compressor (not pump), its a compressible gas,
and when it exits, its still a gas, just a bunch hotter and compressed ... gas.
 The water pump is a "pump" because liquid water comes in, and liquid water
comes out, at the same density.  Same with the power steering pump.  Even
though the pressure can go up by 500 or more psi, the density does not change,
or the increase is minute.  Compressors usually require a lot more power than
pumps, because the working fluid "shrinks" as it gets compressed, and also
create more heat.  The incmompressible fluid in a pump behaves itself better,
and as a result, pumps can achieve very large pressure fradients with not too
much power, and generating not as much heat.

D^2

Quoting Kenyon Wills <imperialist1960@xxxxxxxxx>:

> You are a brave man, or one desperately seeking air conditioning.  I have
> avoided the AutoTemp II unit on my car, so can't answer all of those
> questions, but regarding the AC pump: