I wonder if the heat problem in the 145's might be similar to to that experienced in the 135's operated in the middle east. Even with a/c the 135's avionics (efis, fadec and especially autopilot) don't seem to cope with the heat, even after only a few minutes flying.
.....tried a 902 the other day for 2.5hrs at 38' oat, no a/c, (felt about 45' in the cockpit) Everything worked fine.