Air conditioning system fault diagnosis guide (Part 1)
"Refrigeration system low pressure, high pressure value abnormal", "compressor shell temperature abnormality", "air inlet and outlet temperature difference value abnormal", "air conditioner outlet temperature is too high or low", "low pressure pipe frost", "exhaust The temperature of the air pipe is too low or too high", "Condensation in the suction pipe", "The temperature of the fan motor casing is too high", "There is no sound of refrigerant flowing in the capillary tube in the indoor or outdoor unit" ........ What to do with the air conditioning system "Watts"?
Don't be afraid, okmarts.com official media think of a way! We climbed mountains, waded, and crossed the oceans and finally invited "testing experts" --- okmarts.com application engineers to support us.
The okmarts.com application engineer tells everyone that during the installation and maintenance of the air-conditioning system, the operator needs to observe whether the key operating parameters of the system (evaporating pressure, condensing pressure, superheat, subcooling, current, etc.) are normal or not to judge potential failures Source to quickly and accurately find and repair the system. Therefore, for air-conditioning system failures, we need to use accurate measuring instruments and then determine where the air-conditioning system is faulty based on the diagnostic results of the instrument. The correct remedy can cure the disease. This guide is divided into two parts. The previous article provides: 1. Explanation of measurement parameters 2. Measuring instrument and connection method 3. System testing points The next article provides: 1. Comprehensively judge system faults with the help of parameters 2. Normal range of operating parameters 1. Explanation of measurement parameters Air-conditioning system maintenance often faces many complicated low-pressure and high-pressure side parameters as reference for measurement results, so for these parameters "evaporation pressure, condensation pressure, saturated evaporation temperature, saturated condensation temperature, superheat, subcooling" What is your understanding? The following okmarts.com application engineer gives us a simple and popular description of a feature comparison chart.
Measuring instrument and connection method After understanding each group of parameters, how do we ensure the accuracy of the parameters at this time? The Refrigeration Encyclopedia platform here recommends that you use the electronic refrigerant meter series from okmarts.com, which displays the pressure of the high and low pressure ends on the same screen, and can be connected to a temperature probe to realize automatic superheat/subcool calculation. In addition, the instrument has built-in pressure-temperature characteristic curves of more than 60 common refrigerants, which can be easily applied to systems using different types of refrigerants.
The schematic diagram of the connection between the instrument and the system is as follows: The figure below is a schematic diagram of the connection between the okmarts.com detector and the air conditioning system provided by the okmarts.com instrument. From the figure below, we can clearly see the convenient connection between the instrument and the system, simple operation, and intelligent detection, and the results are fast and accurate.
The okmarts.com electronic refrigerant meter set has the highest accuracy in the field of refrigeration measurement, and its performance far exceeds the analog refrigerant meter set. At the same time, the okmarts.com electronic refrigerant meter group can also detect the air tightness of the pipeline, detect even the smallest leaks, and stably record the vacuum process of the system. Measurement points After we understand the meaning of the measurement parameters and have advanced measuring instruments, what points should we pay attention to in the measurement process? The okmarts.com application engineer has listed the following 12 points, which seem to be simple, operate and prudent, let us read it carefully before using it! 1. Before performing any maintenance operations (such as charging refrigerant), make sure that the air volume of the evaporator is in the normal range and that the fan coil, filter, and fan are in a clean state. A 2. Do not charge the refrigerant too fast, because the liquid refrigerant may accumulate in the liquid collector on the low-pressure side, which will cause the refrigerant to circulate in the pipeline for a longer time, which means that the charging speed is too fast Will cause the system to overcharge. A 3. Whether it is charging refrigerant or diagnosing faults, observe the changes in superheat and subcooling at the same time, because only one end of the data can not fully evaluate the system operation status. 4. The air source heat pump can only achieve precise refrigerant charging in the cooling mode. If you must charge the air source heat pump during the heating season, you must ensure that the fan coil is clean and the indoor air volume is within the normal range. It is best to re-verify if the refrigerant charge is appropriate when the next cooling season arrives. A 5. When the air conditioning system throttle type is capillary, use the best superheat to judge the filling. The best superheat depends on the indoor wet bulb temperature and outdoor dry bulb temperature, ranging from 5℃ to 40℃. A 6. The best superheat can be calculated through the okmarts.com electronic refrigerant meter testo 550 or testo 557 with its own App, or consult okmarts.com for the best superheat meter 7. When the throttle type of the air conditioning system is a thermal expansion valve (TXV), a certain pressure drop must be maintained before and after the expansion valve (R22 system is about 6.8bar, R410A system is about 10.9bar) to ensure that the condenser does not produce The refrigerant returns. If the pressure drops below the normal range, the evaporating pressure and condensing pressure may be lower than the normal values, and the actual superheat and subcooling may be higher than the normal values. A 8. When charging a thermal expansion valve (TXV) system, the degree of subcooling is not significantly affected by indoor and outdoor conditions, so such systems often have a relatively fixed optimal value of subcooling. Add refrigerant to make the final subcooling degree within ±3℃ of the optimum subcooling degree. A 9. Because the thermal expansion valve (TXV) cannot adjust the system superheat, when the superheat is too high and the system efficiency is affected, additional heat insulation measures need to be added to the evaporating end pipeline. Generally speaking, when the evaporation temperature exceeds 13°C, the system should be further checked. A 10. When replacing the thermal expansion valve (TXV), check whether the bulb is placed and fixed. Use a metal bandage instead of insulating tape or wire to fix the bulb. A 11. Once the refrigerant charge is correct, do not reconnect the refrigerant meter during routine maintenance. Ninety-five percent of the problems in the air conditioning system are caused by external dirt entering the system. A 12. If possible, measure and verify the cooling capacity of the air conditioning system. To calculate the cooling capacity of the air conditioner, it is recommended to use a thermometer and hygrometer with wet bulb temperature calculation (such as testo 605i) and an anemometer that supports air volume calculation (such as testo 410i), with the help of the okmarts.com smart App, and the cooling capacity calculation that comes with the app Formula, can quickly calculate and evaluate the air conditioning load.
