The main cause of freezing (frost) in the evaporator of automobile air conditioning

Winter is coming, and the evaporator in the car is normally not frost. After frosting, it affects heat transfer, increases thermal resistance, reduces refrigeration effect and air volume, so the evaporator can only condensation. But why the frost, the following Shiyan prick car for you to do the following summary:

1. The adjustment of the expansion valve is too small, and the low pressure is too low;

2, the system refrigerant is too little, evaporation pressure is too low;

3, the inner circulation filter is blocked;

4, temperature control (or temperature sensor) failure, the compressor does not stop;

5, variable displacement compressor energy control valve (pressure regulating valve) failure, the compressor has been working at full capacity, resulting in low pressure is too low and evaporator frosting. Of course, the low pressure level is also affected by ambient temperature and cab temperature. For the tube and belt evaporator, because only one end into the other end out, so the advanced liquid side is colder, and then gradually not cold, this is a common phenomenon in the mulang car. The size of the temperature difference between the left and right of the evaporator is due to many factors, such as the compression efficiency of the compressor, the adjustment performance of the expansion valve, the sealing degree of the evaporator bellows, etc. Don't have too much oil in the system! Do not store oil in the evaporator! The wall thickness of the evaporator should not be too thick! Pay attention to leakage of evaporator!

The compressor will not automatically stop the refrigeration, first of all, should check the cause of non-stop. For example, whether the temperature control temperature packet is in the appropriate position; Whether the temperature control is appropriate (adjust the temperature properly, if not, the temperature control should be replaced); Whether there is a fault in the control of the air conditioning computer.

Evaporator will freeze in addition to the compressor non-stop machine, should also check the evaporation box fan inlet and outlet damper is not blocked; Whether the fan gear is too small (should be opened larger, so that the heat of the cycle is increased, the heat will be better).

Check the control condition of the temperature wind profile system, which is controlled by the servo motor. If there is a malfunction in the windshield system, the air cannot be circulated, and the evaporator freezes.