Are you suggesting that the compressor can auto ignite the oil in an a/c system ? or the gas, should you be using propane?

I think you ought to read this :Fuels and Chemicals - Auto Ignition Temperatures

These temperatures listed only exist inside a diesel engine and to start most diesels it is often only with the aid of glow plugs...ie: An ignition point.

I doubt any refrigerant pump can run at these temps'....and where would the ignition point be ?

The 'hole in the ground' sounds spurious.
.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."