Ok good! Now knowing that, are you venting out a window so the hot air isn't being pulled back into the tent? Like the other grower said 25.6C isn't too bad. Before I turned on my ac the other day I hit temps of 30C and my plants were okay with that for a couple of days while I was hoping the weather would cool down. A big sign of heat stress is the leaves cupping/tacoing.
Another temp solution if you are venting outside, is the use of an air conditioner to cool the room outside the grow space. the cooler the air the exhaust can pull into the tent, the cooler the whole tent will be.