Even in an air-conditioned gym, I always sweated like crazy running on a treadmill, Crankin, so you are not alone. The only things I could find to help were to wear a Halo headband AND run a ceiling fan right above my head AND have a bandanna at the handy to wipe sweat off as it dripped down my face and neck.
I am a BIG sweater. This is why I simply cannot tolerate running right now in Belize. It's extremely humid and 85+ degrees even by 6:30 am now. The sun rises at 5:20 am. It's dry season, so I can't run in the rain, which would be better than in the blistering sun.
I feel so guilty for falling off my regime as I'd been pretty consistently running 3x a week (3-4+ miles) for months until sometime in April. To make matters worse, a new friend of mine who recently moved here used to run marathons and is having no problems running in this heat. I wish I didn't feel competitive with her, but I do. It's really crazy. She's just a much better runner than me and seems to handle the heat better (she's from Mississippi, which may have a lot to do with it). I've never run > 5 miles in my life, and she just went out and ran 6 this morning with no problems (other than sweating a lot).
Urghhhhh...what I wouldn't give for an air-cond'd room with a treadmill about right now!
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flo
2006 Trek Pilot 5.0 WSD "Gloria" - Bontrager Select FIT CRZ+
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Ldy Gel Flo