Methods and systems are provided for carrying out on-board diagnostics of a plurality of components of an exhaust heat exchange system. In one example, degradation of one or more of a heat exchanger and a coolant system fluidically coupled to the heat exchanger may be detected based on a first temperature estimated upstream of the heat exchanger, a second temperature sensor estimated downstream of the heat exchanger, a coolant temperature, and a pressure estimated upstream of the heat exchanger. Also, degradation of a diverter valve of the heat exchange system may be detected based on inputs of a position sensor coupled to the diverter valve.

An expansion tank which comprises a tank having a predetermined volume capacity; an expandable elastomeric bladder in the tank, partitioning tank volume into a liquid-containing portion for holding liquid and a gas-containing portion for holding a gas under a pressure that defines a normal pressurized gas volume when the liquid-containing portion holds a predetermined liquid volume; and a proximity sensor mounted to the tank at the gas-containing portion thereof and adapted to emit an alarm signal when volume of the gas-containing portion is reduced.

An expansion tank which comprises a tank having a predetermined volume capacity; an expandable elastomeric bladder in the tank, partitioning tank volume into a liquid-containing portion for holding liquid and a gas-containing portion for holding a gas under a pressure that defines a normal pressurized gas volume when the liquid-containing portion holds a predetermined liquid volume; and a proximity sensor mounted to the tank at the gas-containing portion thereof and adapted to emit an alarm signal when volume of the gas-containing portion is reduced.

A cooling system of an internal combustion engine includes a first flow passage supplying a cooling medium of the internal combustion engine to a radiator, a second flow passage branching from the first flow passage by a flow control valve to supply the cooling medium to a first heat exchanging portion, a third flow passage provided separately from the first flow passage to supply the cooling medium to a second heat exchanging portion via an on-off valve and a control portion controlling the on-off valve and the flow control valve based on a temperature of the cooling medium.

A cooling system of an internal combustion engine includes a first flow passage supplying a cooling medium of the internal combustion engine to a radiator, a second flow passage branching from the first flow passage by a flow control valve to supply the cooling medium to a first heat exchanging portion, a third flow passage provided separately from the first flow passage to supply the cooling medium to a second heat exchanging portion via an on-off valve and a control portion controlling the on-off valve and the flow control valve based on a temperature of the cooling medium.

There is disclosed a vehicle air conditioner which is capable of achieving protection of an air flow passage without hindrance, even when a temperature sensor which detects a temperature of an electric heater fails. When a detected value of an electric heater temperature sensor detecting the highest temperature among a plurality of electric heater temperature sensors 61 to 64 is in excess of a predetermined threshold value, a controller executes a protecting operation of limiting energization to the electric heater or stopping the energization. The controller calculates an estimated value Thtrest of the temperature which is calculated back from a consumed power of the electric heater, and when one of the electric heater temperature sensors fails, the controller executes the protecting operation on the basis of the highest value among the detected values of the temperature sensors other than the electric heater temperature sensor and the estimated value.

There is disclosed a vehicle air conditioner which is capable of achieving protection of an air flow passage without hindrance, even when a temperature sensor which detects a temperature of an electric heater fails. When a detected value of an electric heater temperature sensor detecting the highest temperature among a plurality of electric heater temperature sensors 61 to 64 is in excess of a predetermined threshold value, a controller executes a protecting operation of limiting energization to the electric heater or stopping the energization. The controller calculates an estimated value Thtrest of the temperature which is calculated back from a consumed power of the electric heater, and when one of the electric heater temperature sensors fails, the controller executes the protecting operation on the basis of the highest value among the detected values of the temperature sensors other than the electric heater temperature sensor and the estimated value.

A method of heating a cabin of a motor vehicle that includes an internal combustion engine operatively connected to an exhaust system having a catalyst, and a heating, ventilation, and air conditioning (HVAC) system is provided. The method includes detecting a request to increase temperature inside the cabin, supplying fuel and air to the engine, and motoring the engine to pump the fuel and air into the exhaust system. The method also includes heating the catalyst to combust the fuel and air inside the catalyst such that a stream of post-combustion exhaust gas is generated. The method additionally includes channeling the generated stream of post-combustion exhaust gas to the HVAC system such that a temperature of a coolant circulated through the HVAC system is increased to heat the cabin. A system configured to perform the above method is also disclosed.

A method of heating a cabin of a motor vehicle that includes an internal combustion engine operatively connected to an exhaust system having a catalyst, and a heating, ventilation, and air conditioning (HVAC) system is provided. The method includes detecting a request to increase temperature inside the cabin, supplying fuel and air to the engine, and motoring the engine to pump the fuel and air into the exhaust system. The method also includes heating the catalyst to combust the fuel and air inside the catalyst such that a stream of post-combustion exhaust gas is generated. The method additionally includes channeling the generated stream of post-combustion exhaust gas to the HVAC system such that a temperature of a coolant circulated through the HVAC system is increased to heat the cabin. A system configured to perform the above method is also disclosed.

Methods and systems are provided for carrying out on-board diagnostics of a plurality of components of an exhaust heat exchange system. In one example, degradation of one or more of a heat exchanger and a coolant system fluidically coupled to the heat exchanger may be detected based on a first temperature estimated upstream of the heat exchanger, a second temperature sensor estimated downstream of the heat exchanger, a coolant temperature, and a pressure estimated upstream of the heat exchanger. Also, degradation of a diverter valve of the heat exchange system may be detected based on inputs of a position sensor coupled to the diverter valve.