Generally speaking, for small studios you have two main options - one is to turn off the A/C when recording or doing critical mixes (final mix for example)
The other option is lots more time and money, and higher priced, slower moving A/C components. Even a standard window unit needs complex baffling unless you're so far away from air routes, neighbors, crickets, dogs, etc that you could just open the door.
Since this doesn't sound like your situation, one of the free-standing, no-hole-in-the-wall units may be your best bet. Just cool things down to a slight shiver, turn it off, record any acoustic parts, stop when it gets too warm and run the AC some more, repeat as necessary.
Saves having to become an acoustic designer just to keep from sweating.
The baseboard heat, while pathetically inefficient, is also the quietest so could be on in the winter whether you're recording or not... Steve