How to block outside air circulation?

[Grenadian]

Yesterday I drove 250km to Grenadier and tested HVAC. As expected, automatic climate control is not working as I want.
One strange thing is that when I turned off HVAC, outside air was coming in.
If this is normal, to block outside air circulation, should I first turn on HVAC and then block outside air intake?

 

[trobex]

Yesterday I drove 250km to Grenadier and tested HVAC. As expected, automatic climate control is not working as I want.
One strange thing is that when I turned off HVAC, outside air was coming in.
If this is normal, to block outside air circulation, should I first turn on HVAC and then block outside air intake?

It's normal. New cars must allow a certain volume per minute or hour to naturally circulate through the vehicle whilst moving. To lower the air volume you would turn your recirculation "on" with AC off.