Air cond. Clutch problem

I replaced the Air Cond. Clutch a few weeks ago, and when I started the engine and turned on and off the Air the clutch seemed to be working fine. I have driven the car only a few times since then and the last time I drove it on the way home I noticed a strange noise comming from the engine compartment. It sounded like a over heating radiator but the temp gage looked fine so I drove just a few miles to home. It turns out that the Air Cond. Clutch was not fully engaged or dise ngaged, it was catching and releasing as if I had not put in on correctly. All of this time the Air Conditioner was NOT turned on.

Anyone know what I might have done wrong. I remember removing the old one in such a fashion that I put the new one on in the same order.