The AC recharge valve on a 2001 Chevy Impala 3.4L V6 is near the firewall. It is the larger of the two tubing.
i have the 3.4 liter 2000 impala and its up against the top of the firewall towards the middle of the engine
on the low pressure side
Under the air filter compartment.
recharge gauge shows pressure of 70 psi
Its located on the accumulator...................
A 2001uses R134a refrigerant.
You may need to recharge the cooling chemical in your unit.
You may have a leak in the system, check that out.