I am not sure how much additional cost there is for the air conditioned rooms in the dorms, but whatever the charge it is worth it. It can and often does get very hot in Osh in summer, over 30C (over 95*F) and I have even one year seen 40*C on a thermometer there. It can even get cool, down in the 50*s F at night, but that is not the norm.
Enjoy it, and by the way when is the best time of year to visit down under?