AC Trouble

I have a 1984 buick century 2.5L. Last summer I had my ac retro fitted, soon after it started making this really loud squealing noise when i have the air on and it is shifting gears. Just recently it starts making the same noise sometimes when i first start it and then it goes away, but it still does it when the ac is on and I shift gears. If anyone has an idea what could be causing this i would appreciate it. Also if anyone has ever heard of the ac like freezing the trany to were it wont shift i would like to hear it. If i park the car and leave it running with the ac on and get back in like 5 minutes later it wont shift pass 45 mph. If anyone can help please do.

The squealing is probably a belt slipping at higher RPM's especially during shifting. I would look for a better belt or look at the tensioner to make it is working correctly and keeping the belt tight. As for the tranny not shifting I never heard of that one especially being caused by AC. I would check the fluid and filter as you may need to change it. However, if it is slipping bad enough that you can't get over 45 then you may need other repairs.