Medium bus, air conditioning expansion valve icing is what s going on

The expansion valve, also known as the throttle valve, is the main component of the automobile air conditioning and refrigeration system, which is installed at the inlet of the evaporator, as shown in Figure 15, and is the dividing point between the high and low pressure of the automobile air conditioning and refrigeration system. Its function is: throttling and decompressing the high-pressure liquid refrigerant from the liquid storage dryer, adjusting and controlling the liquid refrigeration dose entering the evaporator, so that it can adapt to the change of refrigeration load, and at the same time can prevent the liquid hammer phenomenon of the compressor (that is, the liquid refrigerant that has not evaporated is compressed after entering the compressor, which is easy to cause damage to the compressor valve) and the vapor at the outlet of the evaporator is abnormally overheated.

The temperature-sensing expansion valve used in the automobile air-conditioning refrigeration system, also known as the thermodynamic expansion valve, uses the temperature sensing package installed at the outlet of the evaporator to sense the superheat of the refrigerant vapor (superheat refers to the value that the actual temperature of the vapor is higher than the evaporation temperature), so as to adjust the size of the expansion valve opening, so as to control the flow of liquid refrigerant entering the evaporator. When the temperature of the evaporator outlet decreases, the volume of liquid in the chamber of the chamber, capillary tube and membrane shrinks, and the valve port of the expansion valve is closed, thereby restricting the refrigerant from entering the evaporator. Opposite.

If the evaporator outlet temperature rises, the expansion valve grating will open. This increases the refrigerant flow. The internal temperature sensing H type automobile air conditioning thermal expansion valve has a heat insulation column and a guide column at the lower end of the internal temperature sensing pipe, and there is an inner conical sealing ring made of non-metallic materials between the guide column and the valve pin, relying on the deformation when it is stressed up and down, it not only ensures the sensitivity of the valve in the adjustment process, but also makes the gas and liquid cavities of the valve have good sealing performance, so that the internal temperature sensing pipe of the valve can feel the actual temperature of the gaseous refrigerant flowing through the internal temperature sensing pipe, and ensures the normal operation of the refrigeration system and the improvement of refrigeration efficiency.

Wash the air conditioner filter.

The expansion valve of the automobile air conditioner is frozen, and the air conditioner is not refrigerated, which is the ice blockage phenomenon of the refrigeration equipment.

The reasons could be:

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

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

3. The inner circulation filter screen is blocked;

4. The temperature control (or temperature sensor) fails, and the compressor does not stop;

5. The energy control valve (pressure regulating valve) of the variable displacement compressor fails, and the compressor has been working at full capacity, resulting in low pressure and frost of the evaporator;

6. The refrigerant contains water, and the moisture freezes at low temperature, and the ice embolism blocks the capillary, and the refrigeration equipment cannot be refrigerated after the capillary is blocked.

The expansion valve opening is too large or too small will affect the refrigeration effect, in this case, it needs to be adjusted, the packing gland should be loosened before commissioning, twist the adjustment bolt to adjust, and press the cover tightly after adjustment to prevent refrigerant leakage;

Before commissioning, you can estimate the actual working conditions, and when you are close to stabilizing, you can turn the adjusting bolt 1 4 1 2 turns. It is necessary to detect while adjusting, and to detect the stable pressure value. Turn the adjusting screw and observe the low pressure;

Turning the screw clockwise, the spring elasticity increases, the opening of the valve decreases, that is, the flow rate decreases; When the screw is turned counterclockwise, the spring elasticity weakens, and the opening of the valve increases, that is, the flow rate increases. Generally, the screw is rotated once, and the superheat change is about 1.

The principle of air conditioning refrigeration refers to the principle of air conditioning refrigeration operation. After the air conditioner is energized, the low-pressure steam of the refrigerant in the refrigeration system is sucked in by the compressor and compressed into high-pressure steam and discharged to the condenser, and the indoor air is continuously circulated to achieve the purpose of reducing the temperature;

The outdoor air drawn in by the axial fan flows through the condenser and takes away the heat released by the refrigerant, so that the high-pressure refrigerant vapor condenses into a high-pressure liquid, and the high-pressure liquid is sprayed into the evaporator after passing through the filter and throttling mechanism, and evaporates under the corresponding low pressure to absorb the surrounding heat; The cross-flow fan continuously enters the ribs of the evaporator for heat exchange, and sends the cooled air to the room.

1. The zero live wire of the air conditioner power supply is reversed.

Main performance: Generally, it will only appear when the car air conditioner is installed.

Workaround: Reconnect the neutral wire.

2. The fan or capacitor of the internal or external unit is damaged.

Main performance: If the external fan is broken, the main manifestation is that the exhaust temperature is too high or the high pressure is too high; If the internal fan is broken, it will be frosted in the internal unit.

Solution: Replace the damaged internal (external) fan or capacitor.

3. Refrigerant leakage or poor refrigerant quality.

Main performance: The internal and external units of the car work, and the compressor also works, but the car air conditioner has no refrigeration effect.

Solution: Check whether it is caused by leakage or quality problems of refrigerant in automobile air conditioning, and add or replace refrigerant in time.

4. The compressor capacitor is damaged or defective.

Main performance: The internal and external units of the car are working, the compressor will not rotate, and it will cause overheating.

Solution: Check whether the compressor capacitor is in poor contact or damaged, and replace it in time if damaged.

The repair method is to replace the expansion valve, vacuum for an hour, and refill the refrigerant.

It is the expansion valve that is not dredged, and the pressure of the tube is checked.

The expansion valve of the automobile air conditioner freezes, which is the ice blockage phenomenon of the refrigeration equipment, because the refrigerant contains water, and the moisture freezes at low temperatures, and the ice plug blocks the capillary, and after the capillary is blocked, the refrigeration equipment cannot be refrigerated.

The solution is to release all the refrigerant of the refrigeration equipment, vacuum the official circuit, and then fill the refrigeration equipment with qualified refrigerant in a dry environment.

In addition, in order to prevent water from the refrigerant, a drying valve will be welded at one end of the low-pressure pipe, and if necessary, the drying valve will be replaced together, and it is likely to have failed.

Now the quality of this refrigerant is a concern.

This is the ice blockage phenomenon of refrigeration equipment, the reason is that the refrigerant contains water, fault phenomenon: when the compressor starts to work, the capillary temperature quickly drops below 0 degrees Celsius, the moisture freezes rapidly at low temperatures, and the ice embolism blocks the capillary, and the capillary plugs the refrigeration equipment without refrigeration. "After the ice melts off", the capillary is unobstructed and can work normally, and it freezes when it works normally.

And so on and so forth. Repair method: release all the refrigerant of the refrigeration equipment and fill the refrigeration equipment with qualified refrigerant in a dry environment.

Troubleshooting. Your problem is with "just added 5 bottles of Buddha". "Fried" is the refrigerant.

1. All your questions are wrong, the expansion valve is inside, you can't see the icing, it's the evaporator icing, as long as the cause is the blockage of the evaporator blades and the air filter at the tuyere needs to be replaced.

Agree upstairs, if it is not refrigerant, it may be that there is a problem with the expansion logging.

The expansion valve of the automobile air conditioner is blocked by dirt, and it can be blown through with high-pressure air. If the refrigerant leakage in the thermal sensor is caused by the loss of pressure in the power membrane of the expansion valve and all the small particles of refrigerant are blocked, the refrigerant needs to be repaired and filled.

The refrigerant filling with the hose can be carried out according to the following steps: cut off the short capillary on the temperature sensing bag; Enlarge the inner hole with a tip, and use a copper tube about 10cm long with an inner diameter roughly the same as the outer diameter of the capillary to cover the capillary, and weld it firmly with silver or brazing; In addition, a metal joint is processed, which is connected to a low-pressure hose and a high-pressure hose, and the hose is connected to the copper pipe, and the connection is firmly tied with lead wire. Or close the pressure gauge pressure valve and open the low pressure valve.

The green hose is connected to the vacuum pump, then the vacuum pump is started for about 1min, and the fitting is removed to inject refrigerant after it is closed. At the same time, the thermal sensor is immersed in water to find out the leakage, and then vacuum after soldering. After exhausting, it is gradually injected by the pressure of the refrigerant in the cylinder.

Icing is normal, and if you don't want it to freeze, you can add fluoride or adjust the opening pressure appropriately.

If the expansion valve of the air conditioner is frozen, you don't need to repair the expansion valve, just add some fluorine!

It's normal.

It's not normal if it doesn't freeze.

Frost at the outlet screw of the expansion valve of the automobile air conditioner, and the cause and solution of the air conditioner is not cold:

1. The compressor has no refrigerant, add refrigerant.

3. The solenoid valve is not reversed: detect whether the solenoid valve is normal, and replace the solenoid valve if it is not on/off.

4. System failure: check whether the capillary is dirty, oil or ice blocked, if the air conditioner is not refrigerated when refrigerating, it is generally ice blockage, if the nitrogen blowing pipeline blows out the stolen goods or is not smooth, it means that the dirty plug or oil blockage, if there is no refrigerant in the open system, the refrigerant leakage, check the leakage point maintenance.

5. Compressor failure: the whole machine is not refrigerated, open the system, check whether there is enough refrigerant spray, determine whether it is refrigerant leakage, no leakage, and check whether the compressor is not exhausted.

It should be that the expansion valve is slightly blocked!

Causing the expansion valve to be too small and the pressure is too low to cause frost, that's all you can think of for the time being, I hope it will help you.

In addition, the reason why the air conditioner is not cold may also be that you add too much liquid, even if it is an experiment, do not add more refrigerant, so that you will not be able to judge the cause of the fault normally when you turn it on.

When the high-pressure refrigerant liquid condensed by the condenser passes through the throttle valve, the pressure drops due to obstruction, resulting in the vaporization of part of the refrigerant liquid, and at the same time absorbs the latent heat of gasification, and its own temperature is also reduced accordingly, becoming a wet steam at low temperature and low pressure, and then entering the evaporator.

The expansion valve is clogged, which has an impact on the throttling of the refrigerant. The resulting refrigeration effect is very poor.

It is recommended to replace the expansion valve and readd the refrigerant.

I think that as long as it is still refrigerated, it is not broken, and it is not the reason for not using it for a long time.