Hello,

Yes the freely spinning part - where the belt used to sit - is attached to the clutch bearing. It should spin freely without noise or grinding feel. Just smooth spinning. It should not even wobble side to side or front to back.

Grinding feel would indicate early bearing wear - means you still have time - months to few years maybe. Wobbling would indicate badly worn bearing. However I have yet heard of any seized clutch bearing or loose bearing till the pulley comes out. If the compressor is good clutch bearing can be replaced with special tools. The clutch bearing is usually 'roller ball' type and have its own lubrication (sealed). With time it could wear out typically in 5-6 years because this always spins with the engine.

The centre round part is the compressor shaft itself. Its bearing is the 'sleeve' type. Its lubrication comes from the refrigeration oil. If the refrigeration oil is changed every 2-3 years this bearing can last as long as the compressor itself - possible up to 15 years or more. If this bearing seize you have to replace the entire compressor because its shaft also worn out.

In your case I think it is still ok. If it truly binds it couldn't spin at all. A fresh refrigerant oil change could lubricate its innards better and you should be good to go.

Regarding oil change it is very specific to the compressor model as there are three PAG oil viscosity - PAG46, PAG100 and PAG150. Better let the ac specialist handle this. But insist on the correct viscosity for your model as some ac specialist only keep one type of oil for ease of servicing all cars.

Hope this helps.

Amarin.