Air-con compressors draw anything up to about 5Kw on start up. You only have to observe your rev counter or DH engine load reading to see the draw when it and the thermoelectric fans cut in. We get into a certain habit of interrelated movements and rpm synchronization when shifting and the intervention of the aircon system drawing additional power at almost random times, courtesy of the aircon and engine thermostats, yields a second set of rpm/load parameters that your shift movements must accommodate. It is especially noticeable when the air-con cuts in mid-shift, as it messes up your rpm synchronization.
I personally never notice it. And the more power you have, the less noticeable it is.
Solution: more power mod's!!
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18