i live in indiana and have a couple of questions. first, what should the moisture content of 3/4 solid cherry be in this region before installing? also, i have 3/4 particle board over 3/4 plywood can i use air nailer nails long enough to penetrate the sub-floor and leave the particle board or do i need to remove the particle board. Thank you in advance kevin :

I cant help you with you MC question but I am sure some of the clever guys on this forum will have that info for you.
As for the particle board, most nailing systems are limited to 2 inch length on the fastener. This will give you about a 1/4 inch of penetration below the particle board; which in my estimation is not sufficient.

first particle board needs to be yanked out and repalced with plywood or at least osb. The floor should be within 2 points of the subfloor if its plank and 3-4 points if its strip. If the floor conforms to nofa specs it should be between 6 and 9 percent at time of manufacturing.

Poke some of the woodwork inside your home, and then, you will know where the wood needs to be.

If you have started to run the heater inside, it may start drying the woodwork.
You don't want to acclimate to a winter heated interior, as the humidity is pretty low usually from the heater drying the interior air.

With that said, 9% seems to be a good average for Northern Indiana and a little lower closer to 8% in the Southern parts of Indiana.

It is better to have gaps in the winter, than a cupped and buckled floor in the summer.