2000 Chevy Malibu making knocking sound when AC is on

Air inlet or outlet may be clogged, check air filter and catalytic converter, as possibles!

does you motor have knock sensors,they could be bad

Sounds like you have a loose belt on the compressor. Check the engine belt for loosness, or frayed edges (might be time to replace it too). You can put a dab of oil on it- sometimes that will make the sound stop for a short time but the real fix is to tighten or replace the belt.

THE LOUD NOISE IS PROBABLY COMING FROM THE BLOWER MOTOR WHICH IS LOCATED IN THAT AREA. THESE SOMETIMES MAKE A LITTLE NOISE BUT IF THIS NOISE IS LOUD OR JUST DOESNT SOUND RIGHT, THE MOTOR COULD BE GOING BAD.

SOUND LIKE AC COMPRESSOR PULLEY BEARING SEIZING UP.

Call Chevy, I believe this is a Recall.

sounds like a steering column universal gone bad try shaking wheel while in park an look under hood at steering shaft

have the exhaust checked for leaks, a hole in the exhaust or broken pipe will cause a loud engine sound, also is the check engine light on?

it sounds like you have a bad cv axle on the drivers side.

noise is caused by lack of oil to lifters, or worn timeing chain. if noise is from lifters it should go away wit proper oil level, if still there needs timeing chain.