A Honda Accord CD4 car, the user reflects the car's air conditioning is not cooling, and said a few days ago due to damage to the compressor and replaced a new compressor assembly.
    First connect the air conditioning pressure gauge to measure the pressure of the refrigeration system to prove that there is not much refrigerant. Re-holding pressure to keep the pressure to 2.0MPa, hold time 30min, the results of the system without leakage. This is strange, since the system without leakage, then where is the refrigerant from the leakage? In the state of pressure, the author removed the pressure gauge joints, check the high and low pressure tube valve core (Figure 1) seal, but no exception. In order to rule out the possibility of such problems, I still replaced the two valve core. In addition, taking into account the compressor sometimes in the static pressure state does not leak, but in the clutch work will be leaked, so we removed the compressor removed the electromagnetic clutch. After inspection, found that the last increase in the compressor oil is not enough and the color black, while the clutch drive plate and driven plate between the existence of burning traces, can prove that the clutch was slippery. The compressor clutch was re-replaced and the entire air conditioning system (including condenser, evaporator, expansion valve and high and low pressure piping) was cleaned and a storage tank was replaced. After filling the compressor oil about 60mL, installed complex system test pressure normal.
    This is supposed to be no problem, but the start of the engine began to fill the refrigerant when there is an anomaly, plus the first bottle of refrigerant, low pressure table shows no problem, the pressure of about 0.1MPa, high pressure table shows 0. 3MPa; in the finished second bottle, the compressor suddenly issued a large exhaust sound, then the engine began to jitter, the compressor tape began to slip. I observe the pressure gauge, when the low pressure is about 0.15MPa, high pressure table shows 0.5 ~ 0.6MPa, while the engine flameout. After careful observation, it can be seen that the refrigerant is discharged from the pressure relief valve of the compressor cover. We suspect that the compressor may be a problem, so remove the compressor cover to check, but did not find abnormal phenomenon. Then we conducted an analysis, the reason why the pressure relief valve to open, indicating that the pressure of the compressor is too high, and the design of relief valve is also for this purpose. But there is a problem here, since the system pressure is too high, then the pressure gauge should be reflected, but the high pressure meter reading is not high, so we suspect that there is a security risk of pressure relief valve.
    In order to eliminate this risk we re-replaced the compressor cover. By loading the normal pressure test, so they filled the compressor lubricants, and then restart the engine filling refrigerant, the results also reproduce the last scene. At this time the situation so that some of the author puzzled, the change for the system has repeatedly washed 2 times, how will the same problem? After careful consideration, I suspect that there is occasional clogging of the condenser, resulting in the pressure of the compressor is too high. So remove the condenser with compressed air to its internal blowing, actually from the condenser outlet at the exit of a small black plastic sheet. I was pleased, the problem finally found, so with the user to discuss the compressor to the condenser between the high-pressure pipe (Figure 3). Users learned that this situation, said the last time after the repair he ran a long distance, air conditioning on the road there have been no cooling, in the local maintenance from the condenser also blows a black small plastic sheet And retained, compared with the same as this time. So the cause of the fault finally found, the original has been this high-pressure pipe at play.
    The user learned that the front of the car in a car accident a few years ago in a serious damage, was replaced by this root air conditioning high pressure pipe. As the quality of this root canal failed, after several years of use, the internal has been difficult to withstand the high temperature and high pressure air conditioning system, there is the phenomenon of the inner shedding. And when the inner layer of the high-pressure pipe off, the first will enter the condenser, although we have washed three times the condenser, but the cleaning is through, and was in the cold environment. And when the compressor began to work, the adsorbent in the condenser wall of the impurities in the high temperature and pressure began to flow, and ultimately cause the system blockage, but not blocked. When the refrigerant is filled for a certain period of time, the pressure between the compressor and the condenser is actually very high, but since the interface of the high pressure gauge is located on the aluminum tube between the condenser and the drying tank, the high pressure gauge reading Is not a true high voltage. Because the high-pressure table before the interface has been blocked, resulting in a high pressure at one end of the condenser, one end of the pressure display is not high illusion. When the pressure reaches a certain value, the relief valve began to relieve pressure, because the pressure is too high, the clutch began to slip, air conditioning tape began to slip, the engine due to the load is too large and turn off.
    Finally, after replacing the high-pressure pipe, cleaning the condenser, re-filling the compressor oil, and add 700g refrigerant, the low-pressure table shows 0.25MPa, high pressure table shows 1.4MPa, the fault completely ruled out.