Ideally, you would want a 12v DC motor to run the entire system.  A simple
"transfer" switch would allow the power to be routed to the aux.  motor and
the a/c fans and controls.  If memory serves, ac to dc converters are
available from JC Whitney, and the "transfer" switch could be had from a
electrical supply company or even a Home Depot.  The fans and a/c controls
would have to be rewired from the transfer switch so that no current flows
back to the battery and charging system, but I do not think that would be a
problem.

Alan Bosch
Presently:  '82 Rabbit Diesel, '92 Passat CL
Formerly:  '69 Bug, '71 Bug, '73 Bug, '82 Rabbit L, '83 GTi, '88 Fox GL
Sport, '94 Jetta III
In my dreams:  '87 - '91 Westie
"...Fahn, fahn, fahn, auf der autobahn..."