I'm having a loss of A/C under hard acceleration like merging on to an interstate. Air flow from the vents drops off considerably. I read a post by Aye Roll earlier today (I hope he reads this one) that I now can't find where he pointed to a vacuum check valve leak as the possible cause of this problem. Is this the valve on the firewall near the brake master cylinder made by Ate ( black and white in color maybe??)? Many thanks!

bruce