i've searched the net but have foudn exactly my problem ! 1191 japanesse spec 300gt TT (gto)..117 000km..

no coolant leak, fans (both) do get on when i turn ON the AC!, have and after market guage ( cheap one, old owners guage).. so the oem guage is disconnected!

when idleing after a long run the heat grows up to 82-83°C ( it minus 10 here in canada soo no problem when running!).. i've never heard the rad fans on, exept when i turn the AC on.. when ac turned on the heat drop's back to 78°C.. was just wondering what could it be?, at wich temperature does the rad fan should turn on? in °C if possible!.... meaby 82-83 is normal? i have no clue please help me out THX ALOT!!

the air con switch will override the fans, independently of the water system. if the fan is not coming on, run the engine till warm/hot then feel the bottom hose from the radiator - if this is cold I think this idicates either an airlock or blockage or worse case broken waterpump (have you checked there is water in the radiator?. - if this pipe is hot, then possibly a faulty temp switch?
Hope this helps..