Where are the recharging ports for air conditioning on a 3.1 liter Chevy Malibu engine?

There isn't a single "recharging port" for the air conditioning system on a 3.1L Chevy Malibu (or any car for that matter). The refrigerant is added (or removed during servicing) via two ports located on the low-pressure and high-pressure sides of the AC system. These are usually service ports with Schrader valves (like those on your tires) and are typically located near the compressor or condenser.

You won't find them near the engine itself (the 3.1L engine). You'll need to look under the hood, often near the firewall or along the sides of the engine bay, for two low-profile fittings, sometimes colored (typically blue for low-pressure, red for high-pressure, but this isn't always reliable). It's often easier to locate these with a diagram from a repair manual specific to your Malibu's year and model.

Caution: 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.