This AM (i live in New Englnd whee it is very very cold) I noticed a rattle when I first turned the engine over. Popped the hood and noticed that the radiator fan was rattling and one blade was actually contacting the circlular plastic frame that it spins inside ( I could tell when I turned off the car and slowly revolved the fan manually). I could actially touch the fan and stop it and it would then slowly start and pick up speed again (car was running). As the car warmed up the problem went away. I guess I have 2 questions. 1 What would cause this and 2. Although I have never attempted it should I be able to manually..with my hand..stop the fan from rotating? When I let go it spins again obviously. Something tells me that I should not be able to do this but I had never tried before in fear of losing a finger. (this time I was wearing heavy leather gloves) LOL. Let me know what you think. Could the fan clutch ot something like that be gone? Hope it is nothing bad....just the weather but something tells me if it was a hot day my car would be overheating because the fan would not be spinning fast enough.

Thanks in advance
JP