Humidity fluctuating between 40's and 70's in 24hrs

I have a window unit ac in the room. My room is in a shed and the grow room inside it is the only airconditioned part of it. I live in the SE so humidity is HIGH all summer long, it's already pretty high already. I feel like the ac knocks it down to tolerable levels when it's running, but not certain about that, any opinions? Is it safe to rely on just the window unit ac to keep my humidity levels in check? And being early spring the ac doesn't run as much as it will be running in 4 or 5 weeks when summer heat/humidity will be here. So i'm thinking it will keep the humidity more stable when it begins to run more frequently. I also have a fan that i keep on med or high all the time along with a 440 cfm inline fan drawing air outta my room through a carbon filter. Yall think that will be enough to dodge the mold/mildew? I am considering investing in a dehumidifier in a few weeks when i have the money. My plants are still in veg mode now, but i'm flipping to 12/12 in about a week. What should i do? If i need to get a dehumidifier can i afford to wait till my girls are 4 or 5 weeks into flower?

Well what woked for me was I had a de-humidifier for my home already so i adjusted it as i pleased. Mold is a must watch because it can ruin everything. Also get a temp/humidity meter. i had one with temp an % humidity and it was awesome. if you cant afford th dehumid now... i suggest watching the percentage and do te best like air out the room... or try to balance it out with heat/water

You could get a dehumidifier for the early and late summer months and that would help. If it was me (I'm cheap lol). I would not worry to much about humidity if in veg stage. Flower stage is more critical IMO and humidity at that time should be kept low. My flower room relies on passive cooling re intake and exhaust and humidity does get up to 65-70 and i have not had bud rot. Could be just a matter of time but running 3 years now. FYI i do shut it down real soon though for a number of reasons, one being heat.

you need to sort this out only way i can think is de - humidi unit are you growing hydro,in the uk we can buy small yellow boxes that work on the same way has a de humi unit has small white balls in the bottom that collect water cheaper works the same but if you got the money de humidi

Thanks for the info guys. I'll be buying a dehumidifier as soon as i can. Unfortunately thats going to be a little over a month from now. I think they'll be alright until then. I should be about half way through flowering by then. My room is 5x6x7 any suggestions on what size/brand to get? I've seen a few on craigslist that are between 50 and 100 dollars. How many pints should it hold in a room my size?