AC clutch issue

Would like to hear any ones thoughts on this issue.  When the temp. is under about 72 the ac works great. From about 72 to 82  it will run maybe 10 to 15 min. and then shut down.  Over about 82 it may or may not run at all.  I checked the clutch gap and it was a little over the recommended max.  I took off the clutch and removed one of the shims this put the gap right in spec.  Had the same issues, removed the other shim same problem.  When it isn't working the clutch spins a little and stops over and over it is trying to engage.  I now believe the coil is shot and when it gets hot it loses the strength to engage the clutch.  I was able to find and buy a new clutch mechanism in it's entirety.   I have no problem removing the clutch plate after that I'm not sure. I have read some clutches are pressed on some will come right off. In the event it is pessed I have assorted bearing pullers should I be able to use these??  Any ones experience with this please respond.  Also when replacing it would heating up the coil and cooling the shaft help it to slip on easier?   Thanks