CN111071003B

CN111071003B - Method for judging refrigeration mode fault of automobile air conditioning system

Info

Publication number: CN111071003B
Application number: CN201911401120.1A
Authority: CN
Inventors: 李明; 吕然; 江彦; 王永珍
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2021-06-04
Anticipated expiration: 2039-12-31
Also published as: CN111071003A

Abstract

The invention discloses a method for judging a refrigeration mode fault of an automobile air conditioning system, which comprises the following steps: detecting the temperature in the vehicle and the air speed of an air outlet; when T is_{1 Label}‑T₁>ΔT₁An | V₁‑V_{1 Label}︱>ΔV₁At the same time, detect blower signal, if | I₁‑I_{1 Label}︱>ΔI₁Judging that the blower is in fault; and when T is₁‑T_{1 Label}>ΔT₁An | V₁‑V_{1 Label}︱≤ΔV₁And detecting the electric signal of the air mixing door: if | I₂‑I_{2 label}︱>ΔI₂Judging that the air mixing door is in fault; if | I₂‑I_{2 label}︱≤ΔI₂Then, detecting the system high pressure: if the high pressure of the system is higher, the refrigerant is judged to be excessive; if the high pressure of the system is normal or low, whether the expansion valve, the compressor, the condenser and the evaporator have faults or not and the fault types are sequentially judged.

Description

Method for judging refrigeration mode fault of automobile air conditioning system

Technical Field

The invention belongs to the technical field of automobile air conditioners, and particularly relates to a method for judging a refrigeration mode fault of an automobile air conditioning system.

Background

Along with the continuous development of economy in China, the living standard of people is continuously improved, the demand of automobiles is also increased rapidly, the requirement on the comfort degree in a cabin is also correspondingly and continuously improved, and even in a certain sense, the automobiles are not only vehicles, but also can be mobile homes. In order to ensure that the automobile air conditioning system in the optimal state at the moment of temperature, humidity, air cleanliness and the like in the cabin is continuously updated and optimized, the automobile air conditioning system is more complex, meanwhile, as almost all working conditions of the automobile air conditioner are in the automobile driving process, vibration impact and the like exist, the automobile air conditioner has more faults than a household air conditioner, and the fault type is extremely difficult to judge once the faults occur.

At present, most of the advanced vehicle air conditioner fault diagnosis systems generally install a plurality of temperature and pressure sensors in the system, monitor a plurality of state points and judge whether the whole system has faults, and most of the systems can only send out fault alarms and cannot judge specific fault parts or judge fault parts without knowing specific fault types when the faults occur.

Disclosure of Invention

The invention aims to provide a fault judgment method for a refrigeration mode of an automobile air conditioner, which effectively improves the reliability of judgment by acquiring various parameters of temperature, pressure, wind speed and electric signals and can judge specific fault components and fault types step by step.

The technical scheme provided by the invention is as follows:

a method for judging a refrigeration mode fault of an automobile air conditioning system comprises the following steps:

detecting the temperature in the vehicle and the air speed of an air outlet;

when T is_{1 Label}-T₁>ΔT₁An | V₁-V_{1 Label}︱>ΔV₁At the same time, detect blower signal, if | I₁-I_{1 Label}︱>ΔI₁Judging that the blower is in fault; and

when T is₁-T_{1 Label}>ΔT₁An | V₁-V_{1 Label}︱≤ΔV₁And detecting the electric signal of the air mixing door:

if | I₂-I_{2 label}︱>ΔI₂Judging that the air mixing door is in fault;

if | I₂-I_{2 label}︱≤ΔI₂Then, detecting the system high pressure: if the high pressure of the system is higher, the refrigerant is judged to be excessive; if the high pressure of the system is normal or low, sequentially judging whether the expansion valve, the compressor, the condenser and the evaporator have faults or not and judging the fault types;

in the formula, T₁Indicates the temperature in the vehicle, T_{1 Label}Indicating the standard temperature, Δ T, in the vehicle₁Indicating an allowable difference in the in-vehicle temperature; v₁Indicating wind speed at the outlet, V_{1 Label}Indicating standard wind speed, Δ V, at the outlet₁Representing the allowable difference of the wind speed of the wind outlet; i is₁Representing the blower electrical signal, I_{1 Label}Representing standard electrical signals of the blower,. DELTA.I₁Representing a blower electrical signal allowable difference; i is₂Representing the electric signal of the mixing damper I_{2 label}Representing the standard electrical signal, Δ I, of the mixing damper₂Indicating mixing damperThe electrical signal allows for a difference.

Preferably, the system low pressure is detected if the system high pressure is normal or low, wherein:

when the low pressure of the system is low, the front and back pressures of the expansion valve are detected:

if | P₁₁-P₁₂-P_{Valve with a valve body}︱>ΔP_{Valve with a valve body}Judging that the expansion valve is in fault;

if | P₁₁-P₁₂-P_{Valve with a valve body}︱≤ΔP_{Valve with a valve body}Judging that the refrigerant is less;

when the low pressure of the system is higher than the high pressure, the system is judged to be in fault;

in the formula, P₁₁、P₁₂Respectively representing pressures before and after the expansion valve, P_{Valve with a valve body}Indicating the standard pressure difference, Δ P, before and after the expansion valve_{Valve with a valve body}Indicating the allowable differential pressure across the expansion valve.

Preferably, when P is satisfied₂-P_{2 label}>ΔP_{Height of}、P₃-P_{3 Label}>ΔP_{Height of}Or P₄-P_{4 label}>ΔP_{Height of}When one of them is in use, the high voltage of the system is judged to be higher; otherwise, judging whether the high voltage of the system is normal or low;

wherein, P₂、P₃、P₄Respectively representing pressure in different locations of the high-pressure zone, P_{2 label}、P_{3 Label}、P_{4 label}Respectively indicate the internal high voltage region and P₂、P₃、P₄The same position standard pressure; delta P_{Height of}The high pressure zone pressure allows for a difference.

Preferably, the method for determining a failure in a cooling mode of an air conditioning system of a vehicle further includes:

when the low pressure of the system is normal, detecting the outlet pressure of the compressor, wherein:

if P is_{1 Label}-P₁>ΔP₁Judging that the compressor is in fault;

if P is_{1 Label}-P₁≤ΔP₁Detecting the internal pressure of the condenser, and if the condenser has the phenomenon of over-high local pressure or over-low local pressure, judging that the condenser is in localPartial blockage;

in the formula, P₁Indicating compressor outlet pressure, P_{1 Label}Indicating compressor discharge standard pressure, Δ P₁To represent_.The compressor outlet pressure allows for a difference.

Preferably, when P is satisfied_{13 sign}-P₁₃>ΔP_{Is low in}、P_{14 label}-P₁₄>ΔP_{Is low in}Or P_{15 label}-P₁₅>ΔP_{Is low in}Wherein, when one of them is determined to be low system voltage;

when P is satisfied₁₃-P_{13 sign}>ΔP_{Is low in}、P₁₄-P_{14 label}>ΔP_{Is low in}Or P₁₅-P_{15 label}>ΔP_{Is low in}Wherein, when one of them is high, the system is judged to be low voltage;

otherwise, judging that the low pressure of the system is normal.

Preferably, the method for determining a failure in a cooling mode of an air conditioning system of a vehicle further includes: detecting the outlet temperature of the condenser if the condenser does not have the phenomenon of local over-high pressure or over-low pressure, wherein:

if T is₃-T_{3 Label}>ΔT₃Judging that the surface of the condenser has poor heat dissipation;

if T is₃-T_{3 Label}≤ΔT₃Detecting the internal pressure of the evaporator, and judging that the evaporator is partially blocked if the evaporator has the phenomenon of over-high local pressure or over-low local pressure;

in the formula, T₃Denotes the condenser outlet temperature, T_{3 Label}Denotes the condenser outlet standard temperature, Δ T₃Indicating the allowable difference in condenser outlet temperature.

Preferably, the evaporator outlet temperature is sensed if the evaporator is not experiencing localized over-pressure or under-pressure conditions, wherein:

if T is_{2 label}-T₂>ΔT₂Judging that the surface of the evaporator absorbs heat badly;

in the formula, T₂Indicating the evaporator outlet temperature, T_{2 label}Indicating the evaporator outlet standard temperature, Δ T₂Indicating the evaporator outlet temperature allowable difference.

when T is_{1 Label}-T₁>ΔT₁An | V₁-V_{1 Label}︱>ΔV₁Detecting a blower signal, wherein:

if | I₁-I_{1 Label}︱>ΔI₁Judging that the blower is in fault;

in the formula, T₁Indicates the temperature in the vehicle, T_{1 Label}Indicating the standard temperature, Δ T, in the vehicle₁Indicating an allowable difference in the in-vehicle temperature; v₁Indicating wind speed at the outlet, V_{1 Label}Indicating standard wind speed, Δ V, at the outlet₁Representing the allowable difference of the wind speed of the wind outlet; i is₁Representing the blower electrical signal, I_{1 Label}Representing standard electrical signals of the blower,. DELTA.I₁Indicating the blower electrical signal allowable difference.

Preferably, when T is_{1 Label}-T₁>ΔT₁An | V₁-V_{1 Label}︱≤ΔV₁Detecting an evaporator outlet temperature, wherein: if T is_{2 label}-T₂>ΔT₂Judging that the expansion valve is in fault;

in the formula, V₁Indicating wind speed at the outlet, V_{1 Label}Indicating standard wind speed, Δ V, at the outlet₁Representing the allowable difference of the wind speed of the wind outlet; t is₂Indicating the evaporator outlet temperature, T_{2 label}Indicating the evaporator outlet standard temperature, Δ T₂Indicating the evaporator outlet temperature allowable difference.

if T is_{2 label}-T₂≤ΔT₂Then detecting a blend door signal, wherein:

if | I₂-I_{2 label}︱>ΔI₂Judging that the air mixing door is in fault;

in the formula, T₂Which represents the temperature at the outlet of the evaporator,T_{2 label}Indicating the evaporator outlet standard temperature, Δ T₂Indicating an evaporator outlet temperature allowable difference; i is₂Representing the electric signal of the mixing damper I_{2 label}Representing the standard electrical signal, Δ I, of the mixing damper₂Indicating the mix damper electrical signal allowable difference.

The invention has the beneficial effects that:

(1) the fault judgment method for the refrigeration mode of the automobile air conditioner can accurately indicate the fault component and the fault type through step-by-step judgment.

(2) The fault judging method for the cooling mode of the automobile air conditioner provided by the invention can be used for simultaneously acquiring various data parameters of temperature, pressure, wind speed and electric signals, so that the reliability of the system is effectively improved, and the system can judge specific fault components and fault types according to the acquired data.

(3) The invention combines qualitative analysis and quantitative analysis at the same time, can set different allowable difference values for different parameters, thereby reaching the fault allowable range of different levels, namely manually changing the fault limit, and the working temperature of the air conditioner can change along with the change of the environmental temperature.

Drawings

Fig. 1 is a flowchart of a method for determining a cooling mode fault of an automotive air conditioning system according to the present invention.

Fig. 2 is a layout diagram of sensors of the present invention.

Detailed Description

The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.

As shown in fig. 1-2, the present invention provides a method for determining a cooling mode fault of an air conditioning system of a vehicle, and the arrangement positions of sensors and the physical quantities of a fault diagnosis system involved in the present invention are described as follows:

temperature sensors uniformly arranged in the vehicle detect temperature T in the cabin₁；

In-vehicleStandard temperature T_{1 Label}；

Allowable difference value delta T of temperature in vehicle₁；

Air outlet arrangement flow velocity sensor for detecting air outlet air velocity V₁；

Standard wind speed V of air outlet_{1 Label}；

Air outlet wind speed allowable difference value delta V₁；

An electric signal sensor arranged at the blower detects the electric signal I of the blower₁；

Blower standard electrical signal I_{1 Label}；

Blower electrical signal allowable difference value delta I₁；

The evaporator outlet arrangement temperature sensor 21 detects the outlet temperature T₂；

Standard temperature T of evaporator outlet_{2 label}；

Evaporator outlet temperature allowable difference Δ T₂；

Mix throttle department arranges electric signal sensor and detects mix throttle electric signal I₂；

Standard electric signal I of mixing air door_{2 label}；

Allowable difference value delta I of electric signals of mixing air door₂；

A plurality of pressure sensors 2, 3 and 4 are uniformly arranged in the high-pressure area to detect the high-pressure P of the system₂、P₃、P₄；

Standard pressure P at the same position in high pressure region_{2 label}P_{3 Label}P_{4 label}；

Allowable difference Δ P of pressure in high pressure region_{Height of}；

A plurality of

pressure sensors

13, 14 and 15 are uniformly arranged in the low-pressure area to detect the low-pressure P of the system₁₃、P₁₄、P₁₅；

Standard pressure P at the same position in low-pressure area_{13 sign}P_{14 label}P_{15 label}；

Allowable pressure difference Δ P in low pressure region_{Is low in}；

Pressure sensors

11 and 12 arranged in front of and behind the expansion valve detect the front and rear pressures of the expansion valveForce P₁₁、P₁₂；

Standard pressure difference P before and after expansion valve_{Valve with a valve body}；

Differential pressure allowable difference value delta P between front and back of expansion valve_{Valve with a valve body}；

Compressor outlet arrangement pressure sensor 1 detects compressor discharge pressure P₁；

Compressor outlet standard pressure P_{1 Label}；

_.Compressor outlet pressure allowable difference Δ P₁；

A plurality of

pressure sensors

5, 6, 7, 8, 9 are uniformly arranged in the condenser for detecting the partial pressure P of the condenser₅、P₆、P₇、P₈、P₉；

Standard pressure P of condenser at same position_{5 Biao}P_{6 Mark}P_{7 label}P_{8 mark}P_{9 sign}；

Allowable pressure difference Δ P in condenser_Cold；

Condenser outlet arrangement temperature sensor detects 10 condenser outlet temperature T₃；

Standard temperature T of condenser outlet_{3 Label}；

Condenser outlet temperature allowable difference Δ T₃；

A plurality of

pressure sensors

16, 17, 18, 19 and 20 are uniformly arranged in the evaporator to detect the local pressure P of the evaporator₁₆、P₁₇、P₁₈、P₁₉、P₂₀；

Standard pressure P at the same position of evaporator_{16 label}、P_{17 sign}、P_{18 label}、P_{19 label}、P_{20 mark}；

Pressure allowable difference Δ P in evaporator_{Steaming food}。

The specific judgment process is as follows:

firstly, a temperature sensor is arranged in the cabin to measure the temperature T in the cabin₁And will T₁And standard design temperature T in cabin_{1 Label}Comparing, judging whether the temperature in the cabin is normal or not, and taking the agent T as₁-T_{1 Label}︱≤ΔT₁The system is considered to have no fault when the temperature is normal; moment T₁-T_{1 Label}︱>ΔT₁Considering that the temperature in the cabin is abnormal and a fault exists, continuously detecting according to the following two conditions:

one, when T_{1 Label}-T₁>ΔT₁The temperature in the cabin is considered to be lower

Under the condition, whether the wind speed of the air outlet is normal is firstly detected, and when the liquid is an agent V₁-V_{1 Label}︱>ΔV₁Considering that the air quantity of the air outlet is abnormal, further judging whether the electric signal of the blower is normal or not because the temperature in the cabin is low due to the high air quantity, and taking an | I as the condition₁-I_{1 Label}︱≤ΔI₁If an unknown fault exists when the air blower works normally₁-I_{1 Label}︱>ΔI₁If the electric signal of the blower is abnormal, the blower fails; moment V₁-V_{1 Label}︱≤ΔV₁Considering that the air quantity of the air outlet is normal, namely the temperature in the cabin is low due to low air supply temperature, further detecting the outlet temperature of the evaporator, and when T is high_{2 label}-T₂>ΔT₂If the temperature is low, the fault of the expansion valve can be judged, so that more refrigerant in the evaporator is caused, and further more heat is absorbed from the environment to cause the low temperature in the cabin; when T is_{2 label}-T₂≤ΔT₂When the temperature of the outlet of the evaporator is normal, the cold and hot air mixing abnormality is inferred, the electric signal of the mixing air door is further detected, and when the | I₂-I_{2 label}︱>ΔI₂If the electric signal of the air mixing door is abnormal, the air mixing door is judged to be a cold air and hot air mixing door fault, and if an agent I₂-I_{2 label}︱≤ΔI₂The electric signal of the mixing air door is normal and the fault is uncertain.

II, when T₁-T_{1 Label}>ΔT₁The temperature in the cabin is considered to be higher

This is the most common fault of the cooling of the air conditioner of the car, so the detection system is relatively complex. When the temperature in the cabin is detected to be higher, the wind gap air volume is detected whether to be abnormal or not similar to the detection, and when the | V₁-V_{1 Label}︱>ΔV₁The abnormal air quantity of the air outlet is considered to be due to the deviation of the air quantityIf the low temperature in the cabin is higher, whether the electric signal of the blower is normal is further judged, and when the | I₁-I_{1 Label}︱≤ΔI₁Considering that the blower normally works, an unknown fault exists, and an agent I₁-I_{1 Label}︱>ΔI₁When the electric signal of the blower is abnormal, the blower breaks down; moment V₁-V_{1 Label}︱≤ΔV₁If the air outlet air quantity is normal, whether the electric signal of the air mixing door is abnormal is detected, and an agent I₂-I_{2 label}︱>ΔI₂When the electric signal of the mixing air door is abnormal, the temperature of the supplied air is higher due to improper mixing of cold air and hot air, and the temperature in the cabin is higher; moment I₂-I_{2 label}︱≤ΔI₂When the electric signal of the mixing air door is normal, namely the air volume ratio is normal, the fault is that the temperature of the cold air is higher, and the temperature of the mixed air supply is also higher. Detecting the high pressure of the system at the moment, when P₂-P_{2 label}>ΔP_{Height of}、P₃-P_{3 Label}>ΔP_{Height of}Or P₄-P_{4 label}>ΔP_{Height of}When one of the conditions is met, the high pressure of the system is considered to be higher, and the fault is that the refrigerant is more; when P is present₂-P_{2 label}>ΔP_{Height of}、P₃-P_{3 Label}>ΔP_{Height of}Or P₄-P_{4 label}>ΔP_{Height of}Detecting system low pressure when neither is satisfied, when P_{13 sign}-P₁₃>ΔP_{Is low in}、P_{14 label}-P₁₄>ΔP_{Is low in}Or P_{15 label}-P₁₅>ΔP_{Is low in}If one of the pressure values is satisfied, the fault is that the low pressure of the system is low, the refrigerant is low or the expansion valve is blocked, whether the pressure before and after the expansion valve is abnormal is further detected, and if yes, the pressure is generated₁₁-P₁₂-P_{Valve with a valve body}︱>ΔP_{Valve with a valve body}When the pressure difference before and after the expansion valve is considered to be obviously abnormal, the fault is the blockage of the expansion valve, and when the liquid injection is injected₁₁-P₁₂-P_{Valve with a valve body}︱≤ΔP_{Valve with a valve body}When the fault is considered to be less refrigerant; when P is present_13-P_{13 sign}>ΔP_{Is low in}、P₁₄-P_{14 label}>ΔP_{Is low in}Or P₁₅-P_{15 label}>ΔP_{Is low in}One of which is satisfied is considered to beWhen the system low pressure is higher, the expansion valve is in failure, the opening degree is larger, and when P is higher_{13 sign}-P₁₃>ΔP_{Is low in}、P_{14 label}-P₁₄>ΔP_{Is low in}、P_{15 label}-P₁₅>ΔP_{Is low in}、P_13-P_{13 sign}>ΔP_{Is low in}、P₁₄-P_{14 label}>ΔP_{Is low in}Or P₁₅-P_{15 label}>ΔP_{Is low in}When none of the low pressures is satisfied, the low pressure of the system is normal, the outlet pressure of the compressor is detected, and when P is normal_{1 Label}-P₁>ΔP₁When the discharge pressure is lower, the compressor is in failure, P_{1 Label}-P₁≤ΔP₁Considering the pressure at the outlet of the compressor to be normal, detecting the local pressure of the condenser, and if the phenomena that the pressure is respectively overhigh and overlow exist before and after the local pressure, when P is₅-P_{5 Biao}>ΔP_ColdAt the same time P_{6 Mark}-P₆>ΔP_Cold、P₆-P_{6 Mark}>ΔP_ColdAt the same time P_{7 label}-P₇>ΔP_Cold、P₇-P_{7 label}>ΔP_ColdAt the same time P_{8 mark}-P₈>ΔP_ColdOr P₈-P_{8 mark}>ΔP_ColdAt the same time P_{9 sign}-P₉>ΔP_ColdWhen one of the four conditions is met, the condenser is considered to be partially blocked (the number of the pressure sensors in the condenser can be changed according to the flow number of the condenser), when none of the four conditions is met, the abnormal phenomenon of the partial pressure is considered not to exist, the outlet temperature of the condenser is detected, and when T is met, the abnormal phenomenon of the partial pressure is detected₃-T_{3 Label}>ΔT₃When the temperature of the outlet of the condenser is considered to be higher, the surface of the condenser is adhered with foreign matters to cause poor heat dissipation, T₃-T_{3 Label}≤ΔT₃When the temperature of the outlet of the condenser is normal, whether the partial pressure of the evaporator is higher or lower before or after the partial pressure is detected, and when P is higher or lower than P, the temperature of the outlet of the condenser is detected₁₆-P_{16 label}>ΔP_{Steaming food}At the same time P_{17 sign}-P₁₇>ΔP_{Steaming food}、P₁₇-P_{17 sign}>ΔP_{Steaming food}At the same time P_{18 label}-P₁₈>ΔP_{Steaming food}、P₁₈-P_{18 label}>ΔP_{Steaming food}At the same time P_{19 label}-P₁₉>ΔP_{Steaming food}Or P₁₉-P_{19 label}>ΔP_{Steaming food}At the same time P_{20 mark}-P₂₀>ΔP_{Steaming food}When one of the four conditions is met, the evaporator is considered to be partially blocked (the number of pressure sensors in the evaporator can be changed according to the flow number of the evaporator), when none of the four conditions is met, the evaporator is considered not to be partially blocked, whether the outlet temperature of the evaporator is higher or not is detected, and when T is met, the outlet temperature of the evaporator is detected_{2 label}-T₂>ΔT₂When the temperature of the outlet of the evaporator is higher, foreign matters are attached to the surface of the evaporator, which influences the heat absorption of the refrigerant from the environment, thereby causing higher air supply temperature and higher temperature in the cabin; if no abnormity exists, the fault is uncertain.

The fault judgment method for the refrigeration mode of the automobile air conditioner can accurately indicate the fault component and the fault type through step-by-step judgment; the invention effectively improves the reliability of the system by simultaneously collecting various data parameters of temperature, pressure, wind speed and electric signals, and the system can judge specific fault components and fault types according to the collected data. The invention combines qualitative analysis and quantitative analysis at the same time, can set different allowable difference values for different parameters, thereby reaching the fault allowable range of different levels, namely manually changing the fault limit, and the working temperature of the air conditioner can change along with the change of the environmental temperature.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.

Claims

1. A method for judging a refrigeration mode fault of an automobile air conditioning system is characterized by comprising the following steps:

detecting the temperature in the vehicle and the air speed of an air outlet;

when T is₁-T_{1 Label}>ΔT₁An | V₁-V_{1 Label}︱>ΔV₁At the same time, detect blower signal, if | I₁-I_{1 Label}︱>ΔI₁Judging that the blower is in fault; and

if | I₂-I_{2 label}︱>ΔI₂Judging that the air mixing door is in fault;

in the formula, T₁Indicates the temperature in the vehicle, T_{1 Label}Indicating the standard temperature, Δ T, in the vehicle₁Indicating an allowable difference in the in-vehicle temperature; v₁Indicating wind speed at the outlet, V_{1 Label}Indicating standard wind speed, Δ V, at the outlet₁Representing the allowable difference of the wind speed of the wind outlet; i is₁Representing the blower electrical signal, I_{1 Label}Representing standard electrical signals of the blower,. DELTA.I₁Representing a blower electrical signal allowable difference; i is₂Representing the electric signal of the mixing damper I_{2 label}Representing the standard electrical signal, Δ I, of the mixing damper₂Indicating the mix damper electrical signal allowable difference.

2. The method of determining a failure in a cooling mode of an air conditioning system of a vehicle of claim 1, wherein a low system pressure is detected if the high system pressure is normal or low, wherein:

3. The method for determining the failure in the cooling mode of an air conditioning system of an automobile according to claim 1 or 2, wherein when P is satisfied₂-P_{2 label}>ΔP_{Height of}、P₃-P_{3 Label}>ΔP_{Height of}Or P₄-P_{4 label}>ΔP_{Height of}When one of them is in use, the high voltage of the system is judged to be higher; otherwise, judging whether the high voltage of the system is normal or low;

4. The method for determining the failure mode of the air conditioning system of the vehicle as set forth in claim 2, further comprising:

if P is_{1 Label}-P₁>ΔP₁Judging that the compressor is in fault;

if P is_{1 Label}-P₁≤ΔP₁Detecting the internal pressure of the condenser, and judging that the condenser is partially blocked if the condenser has the phenomenon of over-high local pressure or over-low local pressure;

in the formula, P₁Indicating compressor outlet pressure, P_{1 Label}Indicating compressor discharge standard pressure, Δ P₁To represent_.Compressor outlet pressure let-offAnd (6) allowing the difference value.

5. The method for determining the failure in the cooling mode of an air conditioning system of an automobile according to claim 2 or 4, wherein when P is satisfied_{13 sign}-P₁₃>ΔP_{Is low in}、P_{14 label}-P₁₄>ΔP_{Is low in}Or P_{15 label}-P₁₅>ΔP_{Is low in}Wherein, when one of them is determined to be low system voltage;

otherwise, judging that the low pressure of the system is normal;

wherein, P₁₃、P₁₄、P₁₅Respectively representing the pressure of different positions of the low-pressure area; p_{13 sign}、P_{14 label}、P_{15 label}Respectively representing P and P in the low-voltage region₁₃、P₁₄、P₁₅The same position standard pressure; delta P_{Is low in}Indicating the allowable difference in pressure in the low pressure region.

6. The method for determining the failure mode of a cooling mode of an air conditioning system of a vehicle of claim 5, further comprising: detecting the outlet temperature of the condenser if the condenser does not have the phenomenon of local over-high pressure or over-low pressure, wherein:

7. The method for determining a failure in a cooling mode of an air conditioning system of an automobile according to claim 6, wherein the evaporator outlet temperature is detected if there is no local over-pressure or under-pressure phenomenon in the evaporator, wherein:

8. The method for determining the failure mode of the air conditioning system of the vehicle as set forth in claim 1, further comprising:

if | I₁-I_{1 Label}︱>ΔI₁Judging that the blower is in fault;

9. The method as claimed in claim 6, wherein when T is greater than T, the method further comprises_{1 Label}-T₁>ΔT₁An | V₁-V_{1 Label}︱≤ΔV₁Detecting an evaporator outlet temperature, wherein: if T is_{2 label}-T₂>ΔT₂Judging that the expansion valve is in fault;

10. The method for determining the failure mode of a cooling mode of an air conditioning system of a vehicle of claim 9, further comprising:

if T is_{2 label}-T₂≤ΔT₂Then detecting a blend door signal, wherein:

if | I₂-I_{2 label}︱>ΔI₂Judging that the air mixing door is in fault;

in the formula, T₂Indicating the evaporator outlet temperature, T_{2 label}Indicating the evaporator outlet standard temperature, Δ T₂Indicating an evaporator outlet temperature allowable difference; i is₂Representing the electric signal of the mixing damper I_{2 label}Representing the standard electrical signal, Δ I, of the mixing damper₂Indicating the mix damper electrical signal allowable difference.