Air-conditioning is not nearly as commonplace in European hotels as it is in places like North America and Asia. For most of the year it is simply not needed, and a lot of the hotels are in older, historic buildings that were built before air-conditioning was developed.
We always try our utmost to contract hotels with these comforts, however based on the volumes of tourists visiting Europe over the summer, supply simply cannot keep up with demand. We work hard to deliver tours offering the best possible balance of comfort and value, and while most of our hotels offer air-conditioning, we cannot guarantee that all the hotels you stay at on your tour will have air-conditioning in the rooms.
If you find your room does not have air-conditioning and it is uncomfortably hot, we recommend asking the hotel reception if they have a fan, which they are usually happy to provide, if they have them available.