Ambient temperature suitable to continuous running of the CNC controller is within the range of 0~40℃. Installation in a limited space will cause ambient temperature to increase beyond this range, because heat is generated from the CNC controller itself, the hydraulic system and coolant system. High temperatures may cause the machine to run out of control or operate erroneously. It also causes various parts of FA-20/CNC to lose quality. Therefore, forced air-cooling is needed if sufficient air circulation cannot be obtained by natural convection.