Temperature inspection and testing are crucial steps in the maintenance of commercial central air conditioning systems. This is because all components of the central air conditioning system have their normal temperature range, and exceeding this range is considered an abnormal state. The factors that cause these abnormalities may be malfunctions or incorrect adjustments. Therefore, during the maintenance process, it is necessary to analyze the cause of the problem in detail and promptly handle or inspect it. The temperature status of several unit components is listed below, which will be an important reference for you during maintenance.
1. Compressor discharge temperature
Normal range: When the compressor is in the cooling state in summer, the exhaust temperature is relatively high and cannot be touched by hand. The exhaust temperature of the R22 (refrigerant type) refrigeration system should not exceed around 125 ℃.
Fault: The exhaust temperature is abnormally high, which may be caused by the high suction or condensation temperature of the compressor, so attention should be paid. If the exhaust temperature is too low, you will find that touching the exhaust pipe will not cause burns, which means that the suction temperature may be very low. This situation may be caused by high humidity during compressor operation or insufficient refrigeration dosage in the system. Regardless of the situation, it is necessary to resolve it in a timely manner to avoid more serious malfunctions.
The wet stroke of the compressor can easily damage the valve structure: operating with very little refrigerant can affect the heat dissipation of the motor winding and accelerate the aging of insulation materials.
2. Compressor housing temperature
Normal range: A. The upper casing is affected by the inhalation of steam, and the temperature is relatively low, in a slightly hot or slightly cool range, estimated to be around 30 ℃. There is a possibility of condensation on the surface of the casing around the suction pipe.
B. The heat generated by the electric motor inside the lower casing and the frictional heat carried out by the refrigeration oil are mainly carried out of the casing by steam.
Fault analysis: The surface temperature of the casing has abnormally increased, which is caused by the high suction temperature of the refrigeration system. When hot steam enters the compressor, it absorbs the heat inside the casing, causing the steam temperature to rise and further increasing the surface temperature of the casing. When the suction temperature is too low, the surface temperature of the casing will decrease. Although this situation helps to cool the refrigeration oil and motor winding, it can lead to a decrease in cooling capacity.
3. The temperature of the condenser
Normal range: Under normal circumstances, the front half of the heat dissipation tube is very hot, and its temperature has a slow and gradually decreasing trend. The thermal sensitivity of the rear half of the heat pipe is significantly reduced compared to the front half.
Fault phenomenon: The refrigerant in the rear half of the condenser has gradually liquefied, causing the temperature to reach the condensation temperature and subcooling temperature. However, when abnormal situations occur, the latter half often approaches room temperature (ambient temperature). This phenomenon is usually caused by insufficient refrigeration dosage of the compressor. In addition, if the entire condenser tube is very hot, this may be caused by excessive refrigerant volume, insufficient ventilation, or high ambient temperature.
4. Shell and tube water-cooled condenser
Under normal circumstances, the upper half is relatively hot, while the lower half is warm.
Fault: If the entire shell is not too hot, it may be due to insufficient refrigeration dosage. If the entire shell is very hot, it may be due to insufficient cooling water or poor heat dissipation effect (scaling inside the water pipe)
5. The temperature of the filter
Under normal circumstances, the inhalation tube feels cool and dewy when touched by hand.
Fault: If the filter cools down, it is most likely due to the blockage of the filter mesh by sludge, causing the filter to not flow smoothly. When the refrigerant flows through the filter mesh, throttling occurs. If the filter is not hot and is at the same temperature as the ambient temperature, it is mostly due to the complete blockage of the filter mesh, which prevents the refrigerant from flowing
6. Temperature of the suction pipe
Under normal circumstances, when we touch the inhalation tube, we feel it is very cool and there is dew forming. But once a malfunction occurs, the suction pipe will become too cool, with too much dew and even cause extensive condensation on the machine. This situation is usually due to excessive refrigerant flow, causing the liquid to not completely vaporize in the evaporator, resulting in liquid reflux. On the contrary, if the suction pipe is not cool, there is no condensation, and the casing is hot, then the problem is usually due to a low refrigerant flow rate or insufficient refrigerant usage. This will lead to an increase in exhaust temperature, a decrease in cooling capacity, and thus affect the overall operation of the machine. To ensure the best refrigeration effect, we need to continuously adjust the flow rate and amount of refrigerant to ensure the normal operation of the system.
7. Temperature of thermal expansion valve
Under normal circumstances, the lower half of the expansion valve is very cold and there is dew, and the sound of refrigerant flow is very dull.
Fault: If the valve body is relatively cold, there is a lot of dew on the surface, or even frost, the refrigerant flow sound is loud (gas flow). This is often due to clogged filter screens or refrigerant leakage in the power box, causing the valve hole to not close properly.
8. The temperature of capillaries
Under normal circumstances, the capillary tube cools and is accompanied by dew, with the sound of liquid flowing;
Fault: If the surface of the capillary tube is very cold and condensation occurs, but the flow sound is loud, it is mostly due to insufficient refrigeration; If the surface of the capillary tube is not cold, does not condense, and does not hear flowing sound, it is mostly due to clogging of the filter or capillary domain
9. Temperature of evaporator
Under normal circumstances, the outer surface of the evaporator is very cold, and its condensed water droplets continuously drip down, causing a large temperature range of 12-14 ℃ for the outlet air. If the surface of the evaporator is not too cold, there is not much dew, or it does not condense, a loud sound of refrigerant flow can be heard, and the temperature difference between the inlet and outlet air is small. Mainly due to insufficient refrigeration dosage or expansion
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