I would echo that the ac is on the edge, or perhaps even technically over what the 15A circiut can provide.
There are four implications:
1) There is some chance that you will trip the breaker- especially at start up, as amperage then can be very high.
2) However, if it's drawing 8, 10 or 14 or whatever-less-than-15 amps the rest of the time, and you house/extension cord, etc, is wired properly, then things should be ok.
3) There is still some chance of a voltage drop since you are "at capacity" (Thus the numerous posters suggesting voltage checks).
4) Running something at capacity, while it should be ok, it still brings up the "you-never-know/overheat/burn-down-the-house" factor and thus the recommendations go bite the bullet and install a 30A hookup.
Thank-you all for the great information, I will most certainly put all this knowledge to good use. It seems to me the easiest will be to change the breaker for a 30 amp and be done with it....I will also be able to run scads of Xmas lights this winter and light up the block....lol
Kona2001 I am guessing the circut in your house has too many other "thing" running on it is why your braker pops. try using a differant plug. I run my 13.5AC all the time even on high from my house wall plug. However I did check by turning off rach breaker untill I found one that had the least load from other "things"
To wa8yxm, That is something I did not think about and should or possibly would have, as I had an electrician install a 30 amp circuit for my garage (a 220 heater) as well as another 30 amp circuit for my hot tub and he also mentioned the size of the wire required to run these circuits, in any case, thanks very much for pointint that out. Also, thanks again to all who answered my concerns, the information has been most helpful and I believe I will look into the instalation of a 30 amp breaker (with the appropriate wire)and carry on from there.