Not sure if your ff A/c thermostat kit is working fine... I read full thread and never see anything from anyone on "automatic A/c trip" ... I got same problem on my Cultus EFi 2007 and mechanic told me that ff automatic mechanism for controlling cooling becomes faulty and either you have to install a fresh Thermostat Kit or have to manually trip the A/c in long runs (1/2 times in 40miles radius with speed of 40km or depends on cooling nature of the cabin). If its a thermostat prob you need to fix it with 600rs only.
Xulfiqar might shed highbeam on the subject which I just raised, as he is more technical & expert... thanks.