Top 3 Reasons Why Electric Air-Conditioning Compressor does not Start?

When the air conditioner compressor of the new energy vehicle owner does not start, it may be due to the following types of failures:

1. Scroll movement failure
2. Motor module failure
3. The compressor motor control module is faulty.

Guchen EAC is here to share with you one of the common failures of the air-conditioning compressor of new energy electric vehicles - compressor startup failure or internal over-current failure.

The compressor stops immediately after a few seconds of starting. This situation is repeated several times in a row, and it is generally judged by the vehicle system that the compressor has failed to start. During the start-up phase, shutdown due to a fault (eliminating over-voltage and under-voltage alarms) is defined as start-up failure. Excessive current will also trigger shutdown protection. The starting failure of the compressor has the same point as the internal over-current fault of the compressor: the effective value of the phase current ≥ the over-current alarm threshold.

The main reason for compressor startup failure or over-current is that the compressor phase current is too large. If the torque required to start the compressor increases, the compressor phase current will also increase accordingly. There are 7 main reasons for the excessive phase current of the compressor caused by the automobile air conditioning system:

1) The electronic fan is not running;

2) The expansion valve is blocked;

3) Other parts of the system are blocked;

4) The amount of refrigerant injected is incorrect;

5) Air enters in the system;

6) The internal structure of the compressor is stuck;

7) The opening of the electromagnetic expansion valve is incorrect;

Therefore, based on the above information, when faced with the vehicle reporting compressor startup failure or internal over-current failure, the following judgments need to be made based on the on-site situation:

` If the high voltage electric compressor fails to start and an internal over-current fault is reported, the system will be evacuated and the refrigerant will be refilled, and the compressor will be refilled with refrigerated oil. After a period of shutdown, it can start normally, and the high and low pressure pipelines of the compressor system normal. It means that the problem is the system itself and has nothing to do with the compressor motor control module.

a If the compressor stops for a period of time after the start of the compressor fails, the refrigerant is refilled and the compressor refrigerated oil is also refilled. The rest of the systems are operating normally, and the pressure of the high and low pressure pipelines of the compressor system is normal, and the compressor still cannot start normally. It means that the compressor itself is abnormal, which can be disassembled and checked.

b After disassembling the machine, if it is found that the outer profile of the orbiting scroll inside the compressor is broken, as shown in the red circle in Figure 1, or the bearing is damaged, it means that the compressor structure is abnormal, otherwise it means that the compressor motor control module is abnormal. , Causing the compressor to fail to start.

c After performing the above steps, analyze the compressor motor control module, and plug the faulty motor control module into the new compressor motor to run. If the operation is successful, it is necessary to check the condition of the original faulty motor, whether there is a poor fit between the compressor motor control module and the motor, and the stator is abnormal. If the operation fails and restarts continuously, it means that the compressor motor control module is abnormal.

Read more information on heat pump electric compressor here.