IS my A/C _supposed_ to work this way?

["Paul M. Moriarty" <pmm>]

Over the weekend, during a heatwave here in the SF Bay Area, I noticed my
A/C behaving in the following manner:

while driving, normal operation.  When stopped at a light, in traffic,
etc... it starts blowing warm air... almost like like the compressor is
disengaging at a time when it's most needed (at least when I'm moving, I can
open the windows :-).

Is this normal behavior for a '97?  If so, is there any way to change the
functionality?

Thanks!

- -> Paul <-