UK the law cover low temperatures with a min but no max, so USA probably have less than that
In the UK we have a min temperature requirment under law, alas there is no upper temperature or indeed any legal requirement to install aircon.
The law has a min of 16 degree's and if manual labouring then 13 degree's and with regards to a upper limit it is mearly defined as reasonable in every aspect. "http://www.hse.gov.uk/contact/faqs/temperature.htm"
So you can resonably assume that managment backs are covered unless somebody dies and then fingers have to be pointed. As nobody died then you can resonably say they were reasonable.