HVAC mold

I’ve had issues on and off with my hvac, house built 2019, we are 2nd owners. Mostly condensation related. I’ve had it looked at and repairs and adjustments have been made. It still condensates enough to drip on plywood beneath. One unit for 2300 sq feet so I know it’s working hard in the summer. It’s in my attic and I live in the south, but hvacs in attics are very common here. Flooding risks I assume? I’ve had mold appear from time to time on my filter, and started to notice what could be mold (it wipes off) on the air vents. I’ve also had dark stains on the plywood below the unit where condensation drips. Two ac guys that have worked on it didn’t seem concerned about mold. Is it worth it to have professional testing done vs an at home test that I send in? Is the more of a common issue that I’m turning into a big deal? I’m not in the market to replace the whole unit and I’m not convinced that this problem wouldn’t reoccur with the new one. I’ve got maybe 3k to play at best. Any advice?