A picket line set up at the University of Windsor’s central refrigeration plant meant workers could not get in to fix the school's air conditioning system.

About half the buildings on campus were impacted as a level 2 heat alert was issued for the city on Tuesday.

About 280 members of CUPE Local 1393 went on strike on Sunday. The union represents skilled trades and professional staff, including equipment technicians, carpenters and graphic designers.

The university was working on fixing the problem and the Ministry of Labour was also involved.

“It is my understanding that we have had people there around the clock and that the outside contractors has respected our picket lines,” says Aldo Dicarlo, strike coordinator for CUPE 1393.

Outside contractors were brought in to fix the cooling system after a safety issue was brought to light by a worker with Unifor local 2458 about six months ago.

“One of the engineers told me if something had gone array it could have been as bad as one of them losing a limb," says Mike Kisch, Unifor Local 2458.

Officials say the Ministry of Labour issued work orders Tuesday morning. The university says it will be fixed by Wednesday.

In the meantime, some professors came up with their own solutions, such as taking their classes outdoors.

Some students say they'll tough it out, while other say they’ll sit classes out for now.