The proceedings will resume Monday in Broward County, the Miami Herald reported. Lawyers for Matthew Bent are expected to put on one witness, ending testimony in the case.
Circuit Judge Michael Robinson sent the jury home in early afternoon because the air conditioning in the courtroom was out.
"It is not bearable,'' Robinson said. "It is not something that civilized society should put a jury through."
The victim, Michael Brewer, testified Thursday, describing the attack in October 2009 when he was 15. He said Bent chased him following an after-school dispute.
Brewer was allegedly set on fire after being doused with rubbing alcohol. He said he could not see his attackers, who have pleaded guilty, and believes Bent was trying to distract him.
"I just remember a cold liquid going down my back,'' Brewer said, "and I started walking, and I started feeling burning, and then I started running.''
Brewer climbed a fence and threw himself into a swimming pool. He survived with burns over 65 percent of his body.