Jeff,

Your question is a bit confusing. Most of us are assuming that
you are asking if you can have two different fan speeds - one lower
speed for heating and a higher speed for AC. If so, then the answer
is "usually." Many fan motors have multiple taps for multiple
speeds and it is pretty easy to determine how to change those
taps IF you know what you are doing. If not, then get some advice
from somebody who has done this many times or integrate this
simple modification with a routine service call for HVAC maintenance.
The pro shouldn't charge you too much extra to "rewire" the motor
as long as he is already out to your home for the annual maintenance
call.

Also, many tract home developments built around 40 years ago
had the same furnace, AC and ductwork in most of the homes. If
you locate a neighbor with the same setup as yours, then you can
check out which taps are being used on his fan. This isn't 100%
guaranteed, but it is usually safe. Many of us could make a good
educated guess on which taps and fan speeds should be used, but
I'm not going to make that blind suggestion over a newsgroup.

Final comment: Be certain that whoever pulls out that fan/blower
assembly cleans the squirrel cage if needed and lubes the motor.
Fins on the squirrel cage can get clogged with dust, especially if
the home has every had an electronic air filter which was neglected.
Also, some motors are difficult to lube and some HVAC guys skip
one or both oil ports on the motor.

Good luck,
Gideon