Hot air conditioning failure, excavator air conditioning failure summary

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Air-conditioning system failure
First, the air-conditioning refrigeration is poor
Fault phenomenon: The air conditioner is not cooled after 2 hours of use, and it can work normally for a period of time after 2 hours of turning off the air conditioner.
Fault analysis: 1, the temperature sensor is damaged or the insertion position is incorrect, resulting in incorrect temperature sensing signal, which automatically cuts off the compressor power supply;
2, expansion valve icing;
3, refrigerant filling too much or too little or residual air;
4, drying cylinder saturation;
5, the condenser heat dissipation is poor, resulting in the air conditioning system to protect the compressor, automatically cut off the power source.
Troubleshooting reason: This kind of failure is mostly caused by air in the system, or impurities, and water caused by ice blocking.
1, the air conditioning open refrigeration effect is good, can work for 2 hours, basically can exclude the refrigerant filling amount, but does not exclude whether the vacuum is pumped well;
2. Check whether the relay is damaged and can not be removed, causing the expansion valve to freeze;
3, whether the expansion valve is too small to cause icing blockage;
4, the temperature sensor damage can not give a signal or caused by bad contact with the evaporator;
5. The drying cylinder is saturated.
Troubleshooting method:
1, vacuum again to maintain pressure, check whether leakage, normal after adding refrigerant (low pressure 1-2kg, high pressure 14-16KG);
2, check the compressor clutch can be normal clutch;
3, found that the expansion valve ice, adjust the expansion valve opening to the maximum, check the relay normal, test 2 hours or ice.
4. Open the evaporator and find that the temperature sensor is wrapped in a fixed latch, pull out 2 cm and install it outside the evaporator, reinstall the test, the air conditioner can work normally, and confirm that the fault is when the sensor cannot give a signal at the time of setting the temperature.
Exhaust experience
1, the air conditioning temperature sensor installation position is very important, can not be randomly inserted; Can not be inserted too deep, can not be too shallow, otherwise the induction temperature is not allowed, resulting in poor refrigeration.
2, step by step from the simplest to eliminate, patient to deal with every problem.
Fault case 2
Symptom: A 215C-8 air conditioner does not cool.
Fault analysis:
1, the air conditioning compressor is not powered;
2, air conditioning compressor relay, blower relay power is poor;
3, the control panel is bad;
4, the air conditioning filter is dirty.
Cause of failure:
1, the control panel is broken, resulting in no power circuit;
2. Compressor relay is broken.
Troubleshooting method:
1. Short connect two relays with a wire respectively. When the compressor relay is short-connected, no sound of suction is heard on the compressor, and the relay does not suck;
2, the replacement of a new relay can hear the sound of the compressor, but also can hear the sound of the relay;
3, connected control panel still no response, check found that the blower relay is normal;
4. Replace the control panel and eliminate the fault.
Experience of exhaust; Check the easy ones first, then work your way down.
Fault Case 3
Fault symptom: The user's air conditioner does not cool, the air conditioner control panel has no electricity, the fan does not turn, and the control panel works.
Fault analysis:
1. The air conditioner fuse is damaged due to overload;
2, the air conditioning control panel is damaged;
3, line break;
4, air conditioning refrigeration system lack of refrigerant, pressure is not enough, air conditioning can not start.
Troubleshooting ideas:
1, the power supply is normal, detect the air conditioning refrigerant pressure, normal. Check No. F8 air conditioner fuse, normal;
2, replace the air conditioning control panel, air conditioning control panel is still no power, separate power supply test air conditioning compressor, air conditioning blower motor, are normal;
3, according to the circuit diagram of Sany Factory 135 excavator, no fuse was found in other parts. Measure the wiring harness connecting the air conditioner control panel to the body. All connectors have no voltage. The air conditioning system does not work because there is no power supply to the control panel.
Troubleshooting process:
After careful inspection of the wiring harness of the air conditioner, it was found that there was a glass tube fuse with white sheath in the wiring harness connecting the control panel and the body. After checking that there was no other wear short circuit in the line, a new 5A fuse was replaced, and the test was normal.
Troubleshooting experience:
In the air conditioning system, there are usually two insurance, one way to protect the control part such as the control panel, one way to protect the motor such as the compressor, the blower, the fusing current of the two is inconsistent, and the insurance of the control panel is usually with the air conditioning system, so it is not marked in the circuit diagram. This requires the service engineer to have a certain understanding of the working principle of a certain system component, the structure and layout of the parts, in order to better and faster troubleshoot the excavator.
Suggestion: When assembling the machine, it is best to have more fixed points of the wiring harness to improve the reliability of the wiring harness, and it is recommended to indicate the location and number of insurance in the line diagram.

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