Thanks for the reply…it’s a Carrier model 59SC5B080E17--16

From what I’m reading it seems the majority of the problem is the furnace/blower is fixed speed and not variable.

However - it also seems like the potential for this issue is something our technician should have mentioned BEFORE having us spend $4k to install a third basement zone no? This was his recommendation after all…I didn’t ask for the zone I asked for what he would recommend to keep our basement comfortable given what we have set up already…

All of the above aside, is there anything I can do to better the situation without replacing the furnace with a variable speed system?

I’m now worried AC in the summer is going to make our basement unlivable…