Method and system for diagnosing thermostat fault of engine cooling system

1 . A method for diagnosing a thermostat of an engine cooling system, wherein the thermostat is disposed at an engine coolant path configured to circulate coolant through an engine and a heater core, the heater core being disposed at a rear of an evaporator that is disposed at a heating and cooling path, the method comprising:

receiving, from a heater control module by a diagnostic module, an operating current value of a blower motor configured to operate a blower, the blower being configured to supply outside air to the evaporator;

outputting, by the diagnostic module, a power amount applied to the blower motor for a first certain period of time based on the operating current value of the blower motor;

receiving, by the diagnostic module, a coolant temperature of the coolant;

performing, by the diagnostic module, a fault diagnosis of the blower motor;

outputting a faulty state signal of the thermostat based on the power amount being less than a set operating amount;

outputting a normal state signal of the thermostat based on the power amount being greater than or equal to the set operating amount;

terminating the fault diagnosis of the blower motor based on a target revolutions per minute (RPM) of the blower motor being less than or equal to a first RPM; and

outputting the faulty state signal of the thermostat based on a deviation between the target RPM and a current RPM exceeding a second RPM for a second certain period of time,

wherein terminating the fault diagnosis of the blower motor is performed based on the deviation between the target RPM and the current RPM of the blower motor being less than or equal to the second RPM for the second certain period of time.

2 . The method of claim 1 , wherein outputting the power amount comprises:

outputting the power amount by integrating a product of the operating current value and an operating voltage of the blower motor for the first certain period of time.

3 . The method of claim 1 , further comprising:

before performing the fault diagnosis of the blower motor, outputting the normal state signal of the thermostat based on the coolant temperature exceeding a set temperature,

wherein outputting the faulty state signal of the thermostat is performed based on the coolant temperature being lower than or equal to the set temperature.

4 . The method of claim 3 , wherein the set temperature defines a thermostat opening temperature.

5 . The method of claim 3 , further comprising:

determining whether a run time of the engine exceeds the first certain period of time based on the coolant temperature being lower than or equal to the set temperature; and

comparing the power amount to the set operating amount based on the run time of the engine exceeding the first certain period of time.

6 . The method of claim 3 , further comprising:

terminating the fault diagnosis of the blower motor based on the deviation between the target RPM and the current RPM of the blower motor being less than or equal to the second RPM while the target RPM exceeds the first RPM.

7 . A system for diagnosing a thermostat of an engine cooling system, wherein the thermostat is disposed at an engine coolant path configured to circulate coolant through an engine and a heater core, the heater core being disposed at a rear of an evaporator that is disposed at a heating and cooling path, the system comprising:

a blower motor module configured to operate a blower motor, the blower motor being configured to operate a blower to supply outdoor air to the evaporator;

a heater control module configured to control the blower motor module and to receive an operating current value of the blower motor from the blower motor module; and

a diagnostic module configured to:

receive the operating current value of the blower motor from the heater control module,

output a power amount applied to the blower motor for a first certain period of time based on the operating current value of the blower motor,

receive a coolant temperature of the coolant,

perform a fault diagnosis of the blower motor,

output a faulty state signal of the thermostat based on the power amount being less than a set operating amount, and

output a normal state signal of the thermostat based on the power amount being greater than or equal to the set operating amount,

wherein the diagnostic module is further configured to:

terminate the fault diagnosis of the blower motor and output the faulty state signal of the thermostat based on a target revolutions per minute (RPM) being lower than or equal to a first RPM, and

continue the fault diagnosis of the blower motor based on the target RPM exceeding the first RPM.

8 . The system of claim 7 , wherein the diagnostic module is configured to output the power amount by integrating a product of the operating current value and an operating voltage of the blower motor for the first certain period of time.

9 . The system of claim 7 , wherein the diagnostic module is further configured to:

output the normal state signal of the thermostat based on the coolant temperature exceeding a set temperature, and

wherein the diagnostic module is configured to output the faulty state signal of the thermostat based on the coolant temperature being lower than or equal to the set temperature.

10 . The system of claim 9 , wherein the set temperature defines a thermostat opening temperature.

11 . The system of claim 9 , wherein the diagnostic module is further configured to determine whether a run time of the engine exceeds the first certain period of time based on the coolant temperature being lower than or equal to the set temperature, and

wherein the diagnostic module is configured to compare the power amount to the set operating amount based on the run time of the engine exceeding the first certain period of time.

12 . The system of claim 9 , wherein the diagnostic module is further configured to:

terminate the fault diagnosis of the blower motor based on a deviation between the target RPM and a current RPM being less than or equal to a second RPM while the target RPM exceeds the first RPM; and

output the faulty state signal of the thermostat based on the deviation between the target RPM and the current RPM exceeding the second RPM for a second certain period of time.

13 . The system of claim 12 , wherein the diagnostic module is further configured to correct a model coolant temperature setting value based on the operating current value and an operating voltage of the blower motor, and

wherein the blower motor module is configured to control the blower motor to operate based on the corrected model coolant temperature setting value.