Let's take a look at several common maintenance points of automobile air conditioners.

1. Fault symptom: compressor does not inhale, air conditioning system does not work, and the system has no pressure.

Cause: All refrigerants are leaking.

Troubleshooting: Find out the leakage point (worn pipeline, broken pipeline sealing ring, worn condenser pipe, loose pressure switch, damaged expansion valve, damaged compressor fuse, etc.). ), then replace the faulty parts, vacuumize, maintain the pressure, and fill the refrigerant according to the amount specified in the air conditioning system, and the fault can be discharged.

2. Failure phenomenon: the compressor is inhaled, the air conditioning system does not cool, the surface temperature of the compressor exhaust pipe is very high (hot), and there is no temperature difference between the inlet and outlet pipes of the expansion valve. After the compressor is inhaled, the high pressure remains unchanged and the low pressure is very low.

Cause: The temperature sensing head of the expansion valve was worn, and all the sealed refrigerant leaked, which led to the closure of the valve hole of the expansion valve and the refrigerant circulation could not be realized.

Troubleshooting: replace the expansion valve, then vacuumize, maintain pressure, and add refrigerant according to the amount specified in the air conditioning system, and the fault can be discharged.

3. Fault symptoms: the compressor does not suck, the air conditioning system does not work, and the equilibrium pressure in the system is normal (0.5 ~ 0.7 MPa).

Causes: fuse failure of air conditioning system, failure of air conditioning relay, poor contact or fracture of thermistor lead, poor contact of compressor lead and poor contact of condenser electronic fan lead.

Troubleshooting: Check the above parts, and replace the faulty parts to eliminate the fault.

4. Fault symptoms: the air conditioning system is operating normally, the air conditioning refrigeration effect is not good, the air volume at the air outlet is insufficient, the fan noise is increased, and the evaporator is frosted.

Cause: There is dirt in the air conditioning box passage, which increases the wind resistance and blocks the filter screen.

Troubleshooting: Remove the evaporator core and filter screen for cleaning (once a year), and then reassemble. After installation, vacuumize, maintain pressure, and add refrigerant according to the amount specified in the air conditioning system, and the fault can be discharged.

5. Failure phenomenon: the air conditioner is running normally, the refrigeration effect of the air conditioner is not good, and the high pressure and low pressure are on the high side.

Cause: Too much refrigerant in the air conditioning system or too much lubricating oil in the compressor.

Troubleshooting: Refrigerant should be recovered to release excess compressor lubricating oil, then vacuum, maintain pressure, and add refrigerant according to the amount specified in the air conditioning system, and the fault can be eliminated.

6. Failure phenomenon: The air conditioner works normally, and the cooling effect is getting worse and worse after being used for a period of time, and both high pressure and low pressure are low.

Cause: After the vehicle vibrates during driving, the joint of the pipeline becomes loose, which is caused by the chronic leakage of refrigerant.

Troubleshooting: Re-tighten the joint, then vacuum, maintain pressure, and add refrigerant according to the amount specified by the air conditioning system, and the fault can be discharged.

7. Failure phenomenon: everything is normal when the air conditioner starts to run, but the cooling effect drops obviously after a period of time, until it is not cooled, and the pressure is very high and low (≤0.05MPa). After stopping running for a period of time, restart and return to normal, and repeat the last phenomenon after a period of time.

Cause: The expansion valve is blocked by ice.

Troubleshooting: replace the drying filter, then vacuumize again, keep the pressure, and fill the refrigerant according to the amount specified by the air conditioning system, and the fault can be discharged.

8. Failure phenomenon: After the air conditioning system runs for more than 10 minutes, the air outlet temperature is high, the refrigeration effect is not good, the low pressure is high, and the compressor has knocking sound.

Cause: Expansion valve failure.

Troubleshooting: replace the expansion valve, then vacuumize, maintain pressure, and add refrigerant according to the amount specified in the air conditioning system, and the fault can be discharged.

9. Fault symptoms: the air conditioning system is operating normally, the air conditioning refrigeration effect is not good, the air volume at the air outlet is insufficient, the fan noise is increased, and the compressor is frequently started and stopped.

Cause: There is dirt in the air conditioning box channel, the wind resistance increases and the filter screen is blocked. This is to cut off the compressor and prevent the evaporator from frosting.

Troubleshooting: Remove the evaporator core and filter screen for cleaning (once a year), and then reassemble. After installation, vacuumize, maintain pressure, and add refrigerant according to the amount specified in the air conditioning system, and the fault can be discharged.

10, failure phenomenon: the air conditioning system has high and low pressure, the pointer of the pressure gauge on the high pressure side swings slowly and greatly, and the surface temperature of the compressor exhaust pipe is very high (hot).

Cause: Air is mixed in the air conditioning system.

Elimination method: after the refrigerant is recovered again, vacuum is pumped to the required vacuum degree, and the pressure is maintained and the air is compressed.