Read this in this months fridge mag, trimethyl aluminium is whats made when the methyl chloride in fake R134a reacts with aluminium in compressor etc, it goes bang when when it meets air. Three engineers have been killed so far due to stuff going pop while being fixed. These were reefer unit but some car ac systems have been affected as well. The methyl chloride will eat hoses etc too and turns oil into goo....

Be careful where you get your gas!