FightSafety GIV/G300/G400 PILOT TRAINING MANUAL CHAPTER 11 AIR CONDITIONING INTRODUCTION The air-conditioning and temperature control systems for the Gulfstream IV provide for comfortable cabin and cockpit temperatures throughout the complete operating enve- lope of the aircraft. The normal source of air for air conditioning is bleed air from the engines. The APU is an alternate source and provides heating and cooling of the occu- pied areas when the aircraft is on the ground. An approved external air supply can be connected to an adapter to provide air conditioning on the ground when the other air sources are not available. GENERAL the air-conditioning system consists of a three-wheel air-bearing air cycle machine (ACM) packaged refrigeration unit, in which control over the cabin and cockpit temperature Is accomplished by means of mixing hot com- pressed air and refrigerated compressed air. The dual pack concept provides redundancy 1rt case one unit fails. The term air cycle means that cooling is provided by means of a ther- modynamic cycle, using only air as the medium (as opposed to vapor cycle systems, which employ Freon or other similar gases). The sys- tem also employs water separation for humid- ity reduction. AIR CONDITIONING FOR TRAINING PURPOSES ONLY EFTA01119971