Depends on Baby to baby. you will be able to tell better. Follow your instincts!

Thank you Rhituparna. Does AC temperature or level of fan affect baby?

There's no such fixed rule...but a good indicator if the baby is feeding normally and poop/pee is normal. If not, then it's a red flag for congestion maybe. Else if you notice the baby is wheezing and waking up frequently in sleep, then too it shows that the cold is more than cold / cough.

*cold