northstar,
I wouldn't recommend it, these units are like a refrigeration plant and the Compressor leakage currents that are comon with this sort of equipment could trip the GFCI out.
Just to clarify that statement, I wouldn't personally fit one to any air con or refrigeration gear.
I would however use one on anything else.
Hope this helps.
{Message edited to clarify statement}
[This message has been edited by Trumpy (edited 05-05-2005).]