by Gabe BullardThe last day of classes for Jefferson County Public Schools is Tuesday, and once students leave, contractors will enter many schools to begin upgrading the facilities.The biggest project for crews this summer will be the ten million dollar renovation of the Iroquois High School heating and air condition systems. Winter weather shortened summer break by four days, but Executive Director for Facilities and Transportation Mike Mulheirn says he's confident that workers will finish before classes start in August."Last year, we lost two weeks of construction because of the wind storm and the ice storm," he says. "But our contractors, my hat's off to them, they've geared up and they were able to deliver these projects."Mulheirn says contractors often add extra shifts and work on weekends to finish school jobs on time. In addition to the work at Iroquois, he says there are several other ventilation systems that need repairs.