let me guess, your blower at higher speeds trips and with it AC also goes down as it should be as if one turn off the blower, and after couple of minutes blower automatically turns on and with it AC also kicks in, if you are having same scenario then i am also looking for answer for this phenomenon with my city 2000.
my electrician doubts a faulty blower speed selector switch, though no work have been done on my machine in this regard.
Regards,