A cooling system for a construction machine, which can reduce noise of a cooling fan and can reliably produce cooling air at a required flow rate.
The cooling system comprises a cooling fan 25 for producing cooling air introduced to an intercooler 22, a radiator 23 and an oil cooler 24, a fan hydraulic motor 26 for driving the cooling fan 25, a fan hydraulic pump 27 for delivering a hydraulic fluid to the fan hydraulic motor 26, an air temperature sensor 31 for detecting an air temperature T1 at an outlet of the intercooler 22, a cooling water temperature sensor 33 for detecting a temperature T2 of cooling water for the radiator 23, a working oil temperature sensor 36 for detecting a temperature T3 of working oil for the oil cooler 24, and a controller 29 for outputting a control signal corresponding to a maximum value among calculation values N1, N2 and N3 of cooling fan rotation speed, which correspond respectively to detected values T1, T2 and T3 from the air temperature sensor 31, the cooling water temperature sensor 33 and the working oil temperature sensor 36.