I have a 2012 RX350 and recently have been getting condensation on the outside of my windshield when the AC is running. I have to operate the wipers to clear it up. I tried adjusting the defogger changing from inside air to outside air , turning the blower up full blast . even changing the temperature . nothing works

 

Condensation on the outside has to do with moisture in the air [out side of your vehicle] and you can not do anything other than wait for a change in weather where you live.

The only option you have is to make sure the windshield glass does not become 'cold' as that causes the condensation to happen.
1. make sure the 'cold' air from your A/C is not directed towards the front screen ... keep the mode to auto or vent at the face level and make sure your vents are open to direct majority of the air at face level.
2. Adjust the temp a bit warmer.
3. Turn down the fan so that minimum cold air goes to the screen.
4. Just use the wiper to clean the condensation.

Salim

 

What he ^ said. When it's really humid, just direct the air elsewhere.

 

I had white steam coming out of cabin vents in humid Tennessee summer times. With AC running. Salim is right. None you can do about besides changing air flow direction and raising temp a bit.