Lazy A/C clutch?

I know there have been about 4 million questions on A/C system, but I didn't find this specific issue in the forum.

My 82 300D AC works well (for 134a) except for one possible issue. When I turn on the AC (with ACC) while parked the AC clutch does not engage right away. It seems to engage in less than a minute when I am driving. Also, it will engage with a VERY light tap on the clutch. I suspect it does not engage until I hit the first bump in the road. Once engaged, it operates correctly and will disengage when turned off. It seem like the clutch is "sticking." I don't know if I should try to lubricate it, because it is working (more or less) acceptably and I don't want to mess it up. Does anyone have experience with this?

Thanks,
Craig