In the Star Wars universe, Stormtrooper helmets are not explicitly described as having air conditioning systems. However, it can be assumed that these helmets, being advanced pieces of equipment, likely incorporate some level of environmental control to ensure the comfort and safety of the troopers wearing them.
Stormtrooper armor is known to have various integrated features, such as comm systems, heads-up displays, and air filtration systems. These features suggest that there may be some form of climate control or air circulation to prevent the helmets from becoming uncomfortably hot or fogged up during missions.
Given the vast technological capabilities of the Galactic Empire in the Star Wars universe, it is reasonable to assume that the Stormtrooper helmets are designed with features to maintain a suitable internal environment for the troopers, even if it is not explicitly stated or shown in the movies or other media.