What causes RPMs to drop when I turn my AC on?

What is your question?

For the past few years, my AC is acting weird. When I turn it on the RPMs drop to below half and then climb back up. It will do this when I am standing still or in idle. The issue doesn't appear to be happening while I am moving. There are times where the air does not come out cold after one of the drops in RPM at times. Is it my air compressor? Dirty/clogged condenser? Could it be the drive belt is slipping and needs replacement?

How long has your 2006 Saturn Ion had this problem?

4+ Years