surge with only a/c

[minytrker]

I have an auto camaro with dual 90 setup, it runs perfect except the owner called and said it surgers with the a/c on some times. I havent had a chance to go and check it out, but what could it be? When I tuned it we drove around for atleast an hour with the a/c on and it was perfect a week ago. Any ideas?

[ringram]

I had a similar issue with fans initially. If the air compensation is a little too much the car will see idle is too high and pull spark that can drop idle too low and it adds to much spark, etc, goes into a cycle with IAC playing catchup too.
For me it was a matter of adding a smaller amount of air in compensation and reducing the under and overspeed spark adjustment.
With the dual 90, Im of the opinion that moving the IAC effective area table down a few spaces makes sence too. As the 90 will flow more air around the blade than stock so the effective airflow at each iac count likey starts off higher than stock.
Not sure if that helps your issue or not.