2015 hyundai tucson cooling/heat issue

Hello, I’m having an issue with my AC/heat.
When I’m driving at high speeds, my car will blow whatever my car was set to when I last turned it on. So if I had the heat on, and turned it off, it’ll blow a lot of hot air when I’m on the highway. Same if I had set it to AC, super cold air air will blow.

I had my blower motor replaced before when it completely went out and wouldn’t turn on on any setting (1, 2, 3, 4). Now it turns on just fine, but will stay on when I’m driving at higher speeds.

Any idea what it could be? My AC ran out of freon too since this issue, I’m sure it’s all related. Air still blows but it isn’t cold anymore.