Your heat strips are coming on. Could be that they are always on, even when it's cooling. As I said before, there's not much to those furnaces and should be extremely easy to troubleshoot. Did the handyman call a real ac company or is it a guy that works solely for the mobile home installer? I'd suggest calling a reputable hvac company on your own. It's costing you plenty...possibly as much as it would have cost to have it fixed properly by a competent tech in the first place.