I read this question on the forums, but didn’t answer it so I will.
The air handler is at a low point where it has to “push” against the outside of your house for support. On warm days, that air pressure changes causing the unit to lose refrigerant and sweat. You may notice condensation dripping from your air handler or inside your home if you look close enough. If you have an evaporator coil in the attic, make sure there are no shady spots around them as heat can build up quickly and cause sweating to occur more often. Also remember that putting something metal near/in front of an AC unit (like a toolbox) can lead to excessive heat or cold under certain conditions which results in excessive sweating because it’s trying too hard.