power problem

i have a 2001 olds alero 2.4L

i have 50.000 miles on it starting yesterday i think i have a problem with the compressor because for some reason when i turn on the a/c or defrost it makes the engine shake a bit more than normal.
the rpm's stay the same so i think it is drawing more power that it needs and the compressor aint kicking in right.
anyone have a sugestions or am i on the right track.

[jackal2000]

might be a bearing?? not a common problem thats for sure.