Could be a weak battery or alternator? The ac or blower fan to be precise does work less under load. Try to pay attention when you're making a turn if it blows less especially a sharp turn which is hard on the power steering pump.
The power steering has been messed up for a while,its so hard to turn the steering wheel.
I replaced the power steering pump didn't help, you have to be really strong to turn the wheel.
I greased the actual rod which runs down to the axle didn't help either.
Battery was replaced not long ago and shows that it's a strong good battery.
The alternator I'm not sure about.