You won't find them near the engine itself (the 3.1L engine). Budete se muset podívat pod kapotu, často v blízkosti firewallu nebo po stranách motorového prostoru, na dvě nízkoprofilové armatury, někdy barevné (typicky modré pro nízký tlak, červené pro vysoký tlak, ale to není vždy spolehlivé). It's often easier to locate these with a diagram from a repair manual specific to your Malibu's year and model.
Upozornění: Working with automotive AC systems involves refrigerant (often R-134a) that is under pressure and can cause serious injury if mishandled. It's best to have this kind of work performed by a qualified technician. Improper handling of refrigerant can also damage the environment.