Possibly stupid AC question

[Pingouin]

This year, I had to refill my AC, but they couldn't find any leak. They told me that if the previous owner didn't run the AC for a while and the fluid stagnated, it would be normal that the pressure dropped.
So, my question: if I turn my AC on, do I have to blow cold air (i.e. set the temperature knob on cold) for the coolant to circulate?
My guess is "no", but I'd rather check with someone better informed!
Thanks!