Boost Reduction with AC on? Options

[Geddes]

It was a fairly hot day today (over 30 degrees celcius) and I was cruising down the highway with the ac on which I don't normally have on.. and noticed that the car was not boosting as per normal..

I know the TSVS setup will reduce boost levels if it thinks its seeing knock, so with the very hot air im assuming it was pulling a bit of boost for that reason, but having the ac system turned on drops the boost even more (I have no actual numbers to give you as I dont have my boost guage hooked up yet), but for comparison, the car with the ac off will peg the boost needle near the top (on a colder day it will hit the plus sign above the top of the guage) but when i turn the ac on, it only makes it to about bar 4 of 6 on the guage..

TLDR version: any one else with a GT-4 with no boost controller installed notice a reduction in boost with the ac on? or is mine just doing something odd..?

for reference, I checked between ac on and off in 3rd gear every time.