Automotive AC Gauge Reading

On-board air conditioners are standard equipment in every car, but some people will find that the air conditioner in their car does not seem to be as cool as when they first bought the car. In this case, it is very likely that there is a problem with the pressure of the air-conditioning pipeline. At this time, we can use the automobile air-conditioning pressure gauge to check whether the automobile air-conditioning refrigeration system is malfunctioning.

How To Read Car AC Pressure Gauges

The air-conditioning pressure gauge contains multiple reading units such as mpa, bar, kpa, psi, etc. Everyone should pay attention to which unit is used (1mpa=10bar=1000kpa=145psi).

Automotive AC Gauge Reading

Generally, automobile air-conditioning pressure gauges are divided into high-pressure gauges and low-pressure gauges. As shown in the figure, the red one is the high-pressure gauge, and the blue one is the low-pressure gauge. The pressure value of automobile air conditioners is generally affected by the environment, engine speed, condenser cooling conditions, and other factors. There is no constant standard. If the outdoor temperature is about 20 degrees Celsius as an example, the high-pressure value of the automobile air conditioner is 1.3 -2.0mpa, low-pressure value 0.12-0.25mpa is normal. If the engine speed is maintained at 1500-2000r/min as an example, the high-pressure value of 1300-1600kpa and the low-pressure value of 150-250kpa during the operation of the automobile air conditioner are normal.

Automotive Air Conditioning Fault Diagnosis

1.Insufficient refrigerant:

both low-pressure gauge and high-pressure gauge are lower than general reading

This situation is relatively common. Some cars may have a long service life and have a slow refrigerant leakage failure, we can directly add refrigerant to solve the problem.

Automotive Air Conditioning Fault Diagnosis

2. Expansion valve failure:

both low-pressure gauge and high-pressure gauge are higher than general reading

The car cooling effect is not good due to the expansion valve is kept in the open status for a long period of time, resulting in a mixture of high and low pressures. Replace the expansion valve to solve the problem.

Automotive Air Conditioning Fault Diagnosis

low-pressure gauge reading shows vacuum and high-pressure gauge are lower than general reading

If the air conditioner has such a failure that a low-pressure gauge goes directly to the vacuum, the car will not be cooled at all. In this type of failure, the evaporator expansion valve is kept in a closed position, and the expansion valve must be replaced.

Automotive Air Conditioning Fault Diagnosis

3. Low-pressure gauge is sometimes normal, sometimes vacuum, high pressure sometimes normal, sometimes low

Encountering this situation indicates that there is water in the system. When the water freezes in the pipeline, it will cause a vacuum phenomenon in the low-pressure pipeline. After the ice is melted, the system is normal again. At this time, release the refrigerant in the system, re-evacuate, and refill the refrigerant.

Automotive Air Conditioning Fault Diagnosis

4. Air conditioner compressor failure:

the low-pressure gauge is higher than general reading and the high-pressure gauge are lower than the general reading

If this phenomenon occurs in the pressure gauge, there is a lot of refrigerant in the pipeline, and the air conditioning effect is not good, then it is necessary to consider the failure of the air conditioning compressor, and replacing the compressor can solve the problem.

Automotive Air Conditioning Fault Diagnosis

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