I noticed that the air vents continue to blow cold or hot air even if its turned off. It seems like this happens on Japanese cars (not only Lexus), but it didn't happen when I had a European car.

Also, my a/c and heat acting strange on my NX, but I'm not sure if its normal or not. For example, my a/c was set at 65F when I turned it off, but the vents would blow 75+ warn air. I have to turn the a/c on for a while and shut it off for it to blow cool / cold air.

 

These are complex and complicated machines with lots of sensors now days, just turn the climate concierge on, set everything on auto and then just set your temperature and forget about everything else.

 

This is the way!

 

The temperature you set your hvac to is the temperature you wish the cabin to get to. Well it has to read the temp in the cabin somehow, so there's a temp sensor I believe just below the start button to the left of the centre screen. It looks like a little grill feature in the dash material. When you first start up the car and the cabin and dash are colder than your setting it'll push out hotter air until the sensor registers desired temp. Visa versa for the warm weather as well. If you want you can force it to get there quicker by turning the temp much further than you wish the car to get to than just adjust back when you're comfy. The system in these cars is very complex, all to conserve fuel and battery energy. Simple solution is to use the Auto feature and climate concierge as mentioned above. It's all there for you to read up on in your manual too.