Cooling system air flow diagnosis

A coolant system for an automobile comprising:

• a heat exchanger adapted to lower the temperature of coolant circulated therethrough;
• an incoming temperature sensor adapted to measure the temperature of coolant entering the heat exchanger;
• an outgoing temperature sensor adapted to measure the temperature of coolant leaving the heat exchanger;
• an air temperature sensor adapted to measure the temperature of ambient air that is flowing into the heat exchanger;
• a computer adapted to receive information from the incoming temperature sensor, the outgoing temperature sensor and the air temperature sensor, the computer further adapted to calculate an Actual Delta T by subtracting the temperature of coolant leaving the heat exchanger from the temperature of coolant entering the heat exchanger, calculate an Expected Delta T, wherein Expected Delta T is a pre-determined value of an expected difference between the temperature of the coolant entering the heat exchanger and the temperature of the coolant leaving the heat exchanger, calculate an Effective Delta T by subtracting Expected Delta T from Actual Delta T, and identify a fault in the air flow through the heat exchanger based on the value of Effective Delta T.

A method of identifying air flow faults within a cooling system of an automobile comprising:

• measuring the temperature of coolant entering a heat exchanger for the cooling system, measuring the temperature of coolant leaving the heat exchanger, and measuring the temperature of ambient air that is flowing into the heat exchanger;
• calculating an Actual Delta T by subtracting the temperature of coolant leaving the heat exchanger from the temperature of coolant entering the heat exchanger;
• measuring a plurality of operating conditions;
• calculating an Expected Delta T by one of, determining a value of Expected Delta T from a look-up table based on the measured operating conditions, and mathematically calculating a value of Expected Delta T based on the measured plurality of operating conditions;
• calculating an Effective Delta T by subtracting Expected Delta T from Actual Delta T;
• repeating the steps of measuring the temperature of coolant entering a heat exchanger for the cooling system, measuring the temperature of coolant leaving the heat exchanger, measuring the temperature of ambient air that is flowing into the heat exchanger, calculating Actual Delta T, calculating Expected Delta T, and calculating Effective Delta T on a pre-determined time interval;
• identifying a condition where air flow through the heat exchanger is above normal based on the value of Effective Delta T being positive;
• identifying a condition where air flow through the heat exchanger is below normal based on the value of Effective Delta T being negative;
• comparing sequential calculations of Effective Delta T;
• identifying a condition where air flow through the heat exchanger is increasing based on the value of sequential calculations of Effective Delta T increasing positively;
• identifying a condition where air flow through the heat exchanger is decreasing based on the value of sequential calculations of Effective Delta T increasing negatively;
• identifying a fault in the air flow through the heat exchanger based on the value of Effective Delta T.