After startup, car not driven for a couple of days, I get a screech from engine compartment. Frequency is function of engine RPM. Screech disappears after about 5 minutes of engine operation, and doesn't reappear until cold start-up after a couple of days sitting. I believe it's the serpentine belt *it does show some wear at 12 years and 73K miles. Anyone care to offer an opinion?

Thanks

 

The belt, the tensioner, the alternator, the AC compressor. Get a mechanic's stethoscope ($5-$10 at HF).

 

 

12 year old belt? Even if it's not worn looking it's probably getting hard and slides on the pulleys until it heats up a bit. So even with low mileage it's over due to be replaced. I neglected mine once and one day it literally fell apart.