Fun fact older refrigerants also broke down into phosgene under high temps. The old school way to identify a compressor burn out was to take a whiff of the refrigerant. If your sinuses started burning from the phosgene then that means you need to do a burn out cleanup.

Newer refrigerants are much more safe, they just break down into hydrogen floride which turns into hydroflouric acid on contact with water. Nothing leaves you quite as invigorated as hydroflouric acid suddenly forming in your lungs, sinuses, throat, and eyes.