Did the electrician install power relay to switch ON the AC compressor? If yes, ask your electrician to convert it back to original wiring. To check this specific condition, the compressor should trip when the ECM sense engine load condition, like on a stand still when the accelerator is abruptly floored. If the compressor is not tripping, it confirms my above statement. Secondly, get the AC signal wire hooked up as I have mentioned in this link
Regarding the temperature gauge, the needle should stay around the mid-point. Anything higher is considered as overheat while lower is considered as colder engine!