2001 impala overheating

2001 impala LS 3.8 liter engine with 140000 miles. the radiator fan on the back of the radiator was makign a really loud noise like something was hitting it, but whe I checked there was no obstruction, and the noise only was present when AC was on. The noise stopped, and the fan stopped moving at all. A week later, the car was overheating quickly(like 10 minutes). I changed the thermostat, but same problem. Do i need to change the whole fan assembly? thanks for any info.

you can change the cooling fan motors individually, so the entire fan assembly doesn't need to be changed. The AC-Delco part numbers are as follows:

Driver's side= 15-8498 (GM dealer #22137318)
Pass side= 15-8490 (GM dealer #22136414)

Do you think your coolant circulates inside the engine? The Belt loose doesn't circulate the coolant, check it to replace/ Ask people about the catalytic convertor (exost) stops maybe the exosted air passing through out through the pipe to back, so makes hot your engine? Ideas. I am not sure excactly why it happens, but such ideas. Just enough the coolant? Imagine the process: low cooland -circulation- belt-convertor-exost pipes....- parts that participate in the process and it will give an idea to fix youself and to save the money! Good luck!

If the coolant temp by the gauge reads lower when you're moving at speed like on the highway, the problem is likely the fans -- they're designed to be controlled at different speeds by the PCM, so a bad one would cause your issue (especailly if it is not running at all because it will block the normal airflow through the radiator) -- electric motors typically get noisy before they die altogether, so replacing the motor will help things get back to normal.

ok thanks!