Relax, Friends. I don't think it is likely anyone will start using ammonia in automotive A/C systems very soon. But I've done a little engineering work with ammonia refrigeration. And ammonia can be dangerous. But let's put it in perspective. Many cars contain about 120 lbs of gasoline. A typical A/C unit would contain maybe 2 or 3 lbs of ammonia. The heating value of gasoline is in the range of 20,000 BTU/lb. Ammonia is 8,000 BTU/lb. The UEL to LEL range for gasoline is 1.2% to 7.1%. That range for ammonia is 15% to 28% (It is far easier to create and explosive mixture of gasoline and air than ammonia and air.)
By my rectal estimate, you would be 150X more likely to get fried by the gasoline in that car that t-bones your diesel, than by some ammonia in the A/C system of your diesel. (Interestingly - the the probablility of getting killed by inhaling or igniting diesel fumes is so low, none of my references even disucss it.) When I was a child, my father had my grandparents' original Fridgidaire refrigerator in his office. That thing had an ammonia charge. We never thought about it being dangerous. When its control circuit burned out after 50 or 60 years of continuous service, it had never lost and ounce of ammonia. My father took it way -- way out back and cut one of the refrigerant lines and ran. When all the ammonia had all gone, he removed the nice little 2 cylinder compressor and used it to fill tires ever since. Ned Kleinhenz '95 E300D x2 '85 300D '80 300TD
