Low cost air circulation for house?

I inherited my parents house and for myriad reasons can’t sell or rent it right now. Selling the house or any of the belongings is off the table. I don’t like using the phrase “stuck with it” in regards to the home I grew up in, but I am stuck with it for a little while. I live and work 3.5 hours away and am only able to go up there maybe once a month if I’m lucky.

The house is in a subtropical climate. It’s a 5br 3br that is made up of the original house and 2 aditions - 1 exterior 1 interior. It has central ac and heat. The 3 bedrooms 2 bathrooms 2 living spaces and kitchen in the oldest part of the house have very low ceilings, no ceiling fans, and floor vents. The 2 bedrooms 1 bathroom and 1 living space in the newer part has higher ceilings with ceiling fans and ceiling vents.

Since I am gone for weeks at a time, leaving windows open isn’t an option. Even when I’m there and leave the windows open, the circulation is very poor. It’s such a maze of a house that there’s just no flow unless the wind is really kicking - and if the wind is really kicking, that means it’s raining which is bringing more moisture into the house.

The side of the house with ceiling fans seems to fare better when I leave the fans on, but the older side w low ceilings not so much. I frequently return to a fine dusting of mold *or mildew (?) on many surfaces and a funky old house smell.

I am not so much concerned about the temperature in the house since it doesn’t take long to heat/cool when I visit. Most of the time the temps aren’t extreme enough that I need to engage the central ac/heat. But I am concerned about the furniture, carpet, and other furnishings with the mold.

Any suggestions for low cost air circulation options that won’t run up the electric bill too high? Like low energy consumption fans or moisture absorption methods? I don’t have anyone in the area at the moment to help out, so it would need to be something that I can leave for a month or 2 and be okay. Thanks in advance for any help!