Unfortunatlly I do not have my AC working. Or is it fortunatly? =8-)

Does it mean that if the clutch leaked it is bad? Should I take it back and get a non leaking one?

I just got to school and had a chance to observe the car in stop and go and highway speeds again. Here is what it did:
When I was waiting to get on the freeway it heated up to about 195F or so. Once I got on the freeway and started going 60mph the temp dropped imediatlly to about 150-160F. YIKES! ( I hope my head will not crack! )
Then it gradually got up to its normall 175F.
Once I hit traffic it stayed at 175-180F, that is sort of normal.

I am begining to think that the coolant is not circulating when I am at idle. I do not know whether its one of the following:
1. air in system. ( how would it get there )
2. bad pump.
3. bad thermostat.
But which one and what order of possibility?
Mark.