"LincTex" wrote in message
...
All airliners basicly use a freon sytem (seldom) or "air
cycle" packs. (common)

Air packs are simple and light, but use a LOT of fuel to operate.

The air packs only consume fuel when the APU is used as an air source, in
flight the engine bleed air is the air source and uses very little if any
extra fuel.