1999 grand voyager 3.3 v6
i had a post a few weeks ago about a whining from the engine like a whiny power steering pump when the a/c is on. its not the fans. it def has to do with the a/c system. we took our first trip in the minivan. it was a 2-1/2 hour ride to our destination. while driving with the a/c on i get alot of jumping jerking from the drivetrain. kind of like a gear kicking in hard. and it does seem to happen when the transmission is shifting or downshifting. but it doesnt happen when the a/c is off. so we decided to ride home with the windows down because of this jerking.
my a/c seems to take alot of power away from my van. now i expect my 91 accord 4cylinder to lose power but not my 3.3 v6 in my van. this compressor is only 1 or 2 years old. i bought this van last fall and seen the paperwork for the compressor. any ideas? i hate to replace an entire compressor for nothing.

 

i think the word im looking for here was "shudder" not jerking
also this seems to happen more when shifting into 3rd or overdrive whichever this van has. we were on interstate doing 70-80 mph. it does it driving around town when shifting in and out of the higher gears, again only when a/c is on.