BAKER — The struggling cooling system at Baker High School failed twice Thursday and may force the cancellation of classes for a third time on Friday, School Superintendent Ulysses Joseph said.

Joseph said students would be notified by automated telephone messages Thursday night if classes are canceled Friday.

Students were sent home early on the first day of school, Aug. 11, and again the next day because of the air conditioning problems.

Joseph said a pump on a chiller unit malfunctioned before classes started Thursday, but the school system’s air conditioning maintenance contractor, Johnson Controls, got it working again.

About 10:30 a.m., however, the pump failed again, Joseph said.

Johnson Controls employees were replacing the pump Thursday afternoon, and Joseph said he would monitor the system Thursday night.

“If it’s not cooling, I’ll make a robo-call to let students know we won’t be having school,” he said.

Joseph said he gave teachers at the school permission to change the locations of their classes to find cooler spots in the buildings. Some classes were held in the gymnasium, he said.

“It was miserable, but we were able to get through it,” Joseph said.