"Contact of 1,1,1,2-tetrafluoroethane with flames or hot surfaces in excess of 250 °C (482 °F) may cause vapor decomposition and the emission of toxic gases including hydrogen fluoride and carbonyl halides."
http://en.wikipedia.org/wiki/1,1,1,2-Tetrafluoroethane
"Upon contact with moisture,including tissue, hydrogen fluoride immediately converts to hydrofluoric acid, which is highly corrosive and toxic, and requires immediate medical attention upon exposure."
http://en.wikipedia.org/wiki/Hydrogen_fluoride
"Carbonyl fluoride is extremely poisonous with a threshold limit value of 2 ppm for short-term exposure."
And you still want to use refrigerant???
There are better solvents simply based on polarity...most are pure unlike butane. Butane is not your only choice and honestly my last resort