I have an older model Carrier furnace for central heat in the basement; the AC unit is newer and outside. I noticed that the Carrier unit has a "Summer Switch". Should it be set to off during the summer months?

Is this a switch on your thermostat or on the compressor unit outside? On in summer.

The summer switch probably just allowes the blower to run all the time. I believe you can just leave it off.

We haven't heard back from Dawg but I have my blower run 24/7 year round. It keeps the three stories from getting stratified.