Air conditioning maintenance tips: Make your cab more cool in summer

Air conditioning systems are essential for today's engineering equipment. Because of the dusty environment and large wind and sand, it is only possible to close the doors and windows to open air conditioners or warm air. The heating system is based on a radiator connected to the engine antifreeze to achieve heating, which is different from the principle of household air conditioning heating.

First, let's first understand the various components and functions of the air conditioning system:

1. Compressor: compressing the refrigerant from low-pressure gas state to high-pressure gas state; 2. Condenser: cooling high-pressure gaseous refrigerant from compressor into high-pressure liquid; 3. Liquid storage tank: also called dry irrigation, with desiccant inside Absorbing water in the system and storing the refrigerant; 4. Expansion valve: atomizing the high-pressure liquid refrigerant to make it a low-pressure liquid; 5: Evaporator: also called an evaporation box, the heat absorption of the refrigerant changes from a low-pressure liquid to a gas state; , Blower: The cold air that is absorbed by the evaporator is blown to the ventilation duct.

Detailed analysis of each component

The first is the compressor. At present, the mainstream of air-conditioning compressors installed on construction machinery and automobiles is swashplate type:

Air-conditioning compressor

The working principle of the swash plate type compressor: the swash plate is fixed with the main shaft of the compressor, and the edge of the swash plate is fitted in the groove in the middle of the piston, and the piston groove and the edge of the swash plate are supported by the steel ball bearing. When the main shaft rotates, the swash plate also rotates, and the swash plate edge pushes the piston to make an axial reciprocating motion.

If the swash plate rotates one turn, the two pistons before and after the pistons are compressed, exhausted, and inhaled for one cycle, which is equivalent to two cylinders. Since the liquid can hardly be compressed, it must be in the full gas state when entering the compressor. If there is too much refrigerant, the refrigerant entering the compressor may have a liquid state, which may damage the compressor.

Second, the condenser: the condenser is generally installed in front of the antifreeze radiator, under the supercooler of the supercharger:

Because there is a certain space under the position, some users like to put some butter barrels, butter guns and other things inside, remind everyone, here is not allowed to put any items, the radiators are copper, aluminum products, hardness is not high, It is easy to affect the heat dissipation effect due to deformation, which causes the air conditioner to be cold.

Third, the liquid storage tank: the liquid storage tank is generally located at the bottom left bottom of the condenser, there must be no water vapor in the air conditioning pipeline, otherwise the ice blocking phenomenon is easy to occur in the liquid storage tank or expansion valve.

Another function of the liquid storage tank is to determine whether the amount of refrigerant is normal. The upper part of the liquid storage tank has a transparent observation window. When the engine speed is stable at 1200-1500 rpm, the air conditioner switch is turned on to check the situation in the window.

(1) Clear, no bubbles, indicating the right amount of refrigerant. Excessive or complete light leakage can be checked by alternately switching the air conditioner. If the instant refrigerant of the air conditioner is turned on or off, it will become clarified, indicating that the refrigerant is in a proper amount; if the air conditioner is turned on or off, the air conditioner is not visible from the mirror, and the air outlet is not cold, between the compressor inlet and outlet. There is no temperature difference, indicating that the refrigerant leaks light; if the air outlet is not cold enough, and there is no air bubble or no flow after the compressor is turned off, it means that there is too much refrigerant.

(2) Occasionally, air bubbles are present, and sometimes there is an expansion valve frosting, indicating that there is moisture in the system. If there is no frosting of the expansion valve, there may be a small amount of refrigerant or air.

(3) There are bubbles and bubbles continue to flow, indicating that the refrigerant is insufficient. If there is a lot of foam, there may be air. If it is judged that the refrigerant is insufficient, it is necessary to find out the cause and do not replenish the refrigerant. Due to the natural leakage of the refrigerant in the hose, if the refrigerant is insufficient after two years of use, it can be judged that the hose is naturally leaking.

(4) There is a long string of oil lines, and there are streaked oil stains on the glass of the observation hole, indicating that the amount of refrigeration oil is too much. At this point, you should find a way to release some refrigeration oil from the system, and then add the right amount of refrigerant. If the oil stain left on the glass is black or has other debris, the refrigeration oil in the system is deteriorated and dirty, and the refrigeration system must be cleaned.

4. Expansion valve: The expansion valve is installed at the inlet and outlet of the evaporation tank. It converts the high-pressure liquid refrigerant into a low-pressure liquid. The refrigerant absorbs the heat and rapidly cools. If there is water vapor in the system, it will cause ice blockage at the expansion valve. The whole system is unreasonable and the pressure is rising. The way to determine if ice is blocked is to use hot water to pour it. If the pressure can return to normal, it is an ice block.

air conditioning

V. Evaporator: The evaporator is located inside the integral blower assembly. The blower controls the damper to select the air duct according to the buttons on the control panel to realize the control of the cold and warm air and the air outlet.

When using the air conditioner, be sure to select the inner circulation. The advantages of this are: 1. The indoor temperature will drop quickly; 2. Avoid external dust entering the condensate mixed with the evaporator to block the evaporator.

When using the inner circulation, pay attention to the cleaning of the filter element in the air conditioner. The inner filter element is usually located at the lower left corner or the middle of the rear of the cab. The filter element can be cleaned with water but not exposed to the sun. It should be dried in a cool place.

6. Blower: At present, the blower assembly for excavators is integrated, which can control the wind speed as well as the wind position.

R134a is currently the mainstream of automotive refrigerants (also R12 after the installation, R12 fluorine will destroy the ozone layer, it is recommended that you do not install this in the installation of air conditioning), the refrigerant also has natural wear and tear, the use time is generally two years. A pressure gauge is used when it is necessary to fill the refrigerant. Blue is a low pressure gauge and red is a high pressure gauge. The nominal units are Kg/cm2 and Psi.

The low pressure range is 1.5-2.5 Kg/cm2, and the high pressure range is 11.5-13 Kg/cm2 (ambient temperature 30-35 °C). When filling the refrigerant, it must be noted that the low-pressure side can only be filled with gaseous refrigerant, and the high-pressure side can only be filled with liquid refrigerant.

It is believed that by knowing the working content of the air conditioning system, the user can find the possible situation of the air conditioning system more quickly at work, and has a cool cab during construction. (This article comes from Smart Revo)