This is one-of-those questions which can be severely over-analyzed and are good for discussions
If the temperature of the final mixture of Sulphuric Acid and water are below the boiling point of water (assuming that the temperature of the Sulphuric Acid-Water mixture does not increase above the boiling point of water at 1 atm - which is another topic we could discuss
), then condensation of air-borne water into the Sulphuric Acid-Water mixture takes place.
When water is condensing, it is now diluting the acid (by dissolution), which creates heat. In this case, condensation of water into a Sulphuric Acid-Water mixture will cause the mixture temperature to increase by two factors: 1) The heat from condensed water is transferred to the mixture (phase change), and 2) water (as condensation) being added to the mixture will impart heat due to the heat of dissolution.
When the temperature of the Sulphuric Acid-Water mixture is above the boiling point of water (again, with the above assumptions), then water is evaporating from the mixture. With this situation, heat is lost due to: 1) water with a phase change (liquid to gas), and 2) a negative heat of dissolution (further concentrating the acid).
I hope this explanation helps. Cheers!