Laws against HEAT in businesses in MA?

There is this Dunkin Donuts in my town that has a very old AC and it freezes over all the time and they have to shut the AC off and the workers are stuck working in it. The owners do not buy any fans no additional AC's.... nothing. Today it was over 100 degrees that the workers had to endure. Are they breaking any law. Is there someone or some organization that could put a stop to it? Anything will help thank you very much