Editor's note: This story was updated to include a statement from an SAISD spokesperson. Students returning to San Antonio ISD's Highlands High School got a chilly surprise Tuesday when temperatures in some classrooms hovered just above 50 degrees due to problems with the campus' heating system. The issue followed less than 24 hours after SAISD Superintendent Jamie Aquino assured families in a Monday email that the district’s HVAC systems were ready to handle this week's cold snap.