Method and system for diagnosing thermostat fault of engine cooling system

Abstract

A method diagnoses a thermostat of an engine cooling system, where the thermostat provided at a heater core installed at a rear end of an evaporator of a heating and cooling path and at an engine coolant path formed to circulate coolant through an engine. The method includes receiving, by a diagnostic module, an operating current of a blower motor configured to operate a blower which supplies outside air to the evaporator; calculating, by the diagnostic module, an accumulated blower operating amount for a certain period of time using the operating current of the blower motor; and comparing, by the diagnostic module, the accumulated blower operating amount with a set operating amount. The method can prevent misdiagnosis of the thermostat by monitoring the blower motor to diagnose whether a fault occurs in the thermostat.