Air conditioner compressor failure Be sure to find out the underlying cause of the compressor failure!
The compressor is the energy core of the air-conditioning refrigeration (heat) system. In the refrigeration system, it mainly functions to compress the refrigerant and promote the continuous circulation of the refrigerating oil. In air conditioning systems, compressors can be divided into three types: reciprocating, rotating and scrolling. Among them, the reciprocating type was used in the early air conditioners and has now been eliminated. At present, the rotary type and the scroll type are more commonly used.
1. Analysis and treatment of air-conditioning compressor failure judgment methods
1. The compressor motor is damaged:
First, the motor is burned out due to incorrect wiring of the compressor terminal;
Second, the system refrigerant leaks;
The high-pressure gas of the rotary compressor is not only discharged from the compressor, but also responsible for taking away the heat generated by the motor. If the system refrigerant leaks, only a small amount of high-pressure gas will be discharged from the compressor, so that the heat generated by the compressor motor will always accumulate when it is energized. If this happens, the compressor motor will burn out.
When the compressor is blocked, the motor should be eliminated as much as possible. Therefore, the insulation resistance of the motor and the windings of the main and auxiliary coils should be measured first to determine whether the motor is burned out.
2. Compressor capacitor problem:
First, the capacitor is damaged (short circuit, open circuit);
Second, the capacitor specifications do not match the compressor.
Note: This item is only applicable to single-phase compressors. Because a three-phase induction motor is used in a three-phase compressor, a rotating magnetic field is generated by passing three-phase alternating current into the stator core, so no capacitor is required.
3. Frequent actions of compressor thermal protection:
First, the thermal protector is abnormal; you can refer to the specifications provided by the compressor manufacturer for the performance diagram and text description of this item;
Second, the wiring of the power cord is unreasonable (the wiring of the compressor terminal is incorrect, or the inverter of the frequency conversion air conditioner is running under phase loss: that is, check the current between the three phases to see if there is a short circuit or open circuit), low voltage start;
Third, start the system before the high and low pressures are balanced; generally, the air conditioner is required to be turned on at least 3 minutes after shutting down; it is also possible that the high and low pressures cannot be balanced as quickly as possible due to the low capillary flow of the system;
Fourth, liquid shock caused by liquid back, long-term shutdown and starting, and starting when the ambient temperature is too low. In the long-term shutdown state and low temperature, the refrigerant in the compressor is dissolved in the refrigerating machine oil to raise the liquid level (the mixture of liquid refrigerant and lubricating oil). When starting, the liquid refrigerant in the enclosed shell It evaporates from the dissolved lubricating oil and produces a strong foaming phenomenon.
4. The compressor has copper plating or rust, that is, water has entered the system:
The refrigeration system has strict requirements for moisture. Generally, it is stipulated that the moisture content in the refrigeration system is less than 0.2ml. If moisture invades the compressor, it will cause serious harm to the compressor as follows:
First: The compressor mechanical parts are plated with copper and rust. When the copper plating and rust reach a certain degree, the clearance between the mechanical parts of the compressor will be reduced, and the compressor may be blocked in severe cases.
Second, the motor coil paint film and insulating materials are corroded, causing the motor to short-circuit;
Third, the deterioration of refrigerant and oil;
Fourth, the leaf spring is embrittled and broken;
In general, the intrusion of moisture may be caused by incomplete vacuum or refrigerant leakage on the low pressure side of the system.
5. Abnormal wear and tear of compressor:
First, the clearance of the internal components of the compressor is small, which is generally a problem of the compressor itself;
Second, the problem of refrigerating oil, such as: poor oil return hole; insufficient oil volume; oil carbonization deterioration, poor oil return, etc.
The refrigerating oil plays a lubricating effect inside the compressor, which can effectively prevent the abrasion of the mechanical parts of the pump body, and its oil seal function can maintain the pressure difference between high and low pressure, avoid high and low pressure gas flow, and prevent the cooling capacity from falling. In addition, due to the continuous circulation of the refrigerating oil, the heat generated between the friction surfaces can be taken away in time. When the amount of refrigerating oil is insufficient, the mechanical parts inside the compressor will be abnormally worn due to the inability to obtain timely lubrication, which will eventually cause the compressor to stall.
There are several reasons for poor system oil return:
First, the length and drop of the indoor and outdoor connecting pipes exceed the specified value; generally, the indoor and outdoor connecting pipes shall not exceed 15m, and the maximum drop shall be 5m.
Second, the capillary of the system is blocked or unreasonably selected and the indoor heat exchanger is not uniformly separated, which causes the refrigerant to return to the compressor without completely evaporating. Since it is not completely evaporated, the flow rate is relatively slow and the refrigerant oil may be attached to the compressor. The tube wall of the heat exchanger causes poor liquid return, which also affects the improvement of the system capacity and the fluctuations.
Third, the system refrigerant leaked away the refrigerating oil, and the refrigerating oil was not replenished when fluorine was added, resulting in poor system oil return.
6. Foreign matter enters the compressor:
The impurities in the compressor and the impurities in the air conditioner system.
2. Air conditioning system failure case
Case 1: The extension tube is not added or the refrigerant is too much
Problem description: 4 sets of 5 HP cabinet machines newly installed in a factory occasionally report exhaust pipe high temperature protection failure. The user thinks it is a machine batch problem and requires the manufacturer to assist in handling.
On-site verification: After arriving at the site, it was found that the 4 cabinets were all about 8-10 meters longer. I asked the master whether there was any leak detection and additional refrigerant during installation. The answer was that no leaks were found during the installation, but no additional refrigerant was found.
Reason analysis: When the extension connecting pipe is not added with refrigerant, it is equivalent to the lack of fluorine in the system. The lack of fluorine in the system will lead to insufficient oil return, poor lubrication of the scroll disk and rise of center temperature, and the exhaust temperature is high. When the temperature reaches At the protection value, the machine displays E4 protection.
On-site treatment: On-site quantitative addition: 50g×8=400g refrigerant, the exhaust temperature is restored to 88 degrees, and after observation for a period of time, the exhaust pipe high temperature protection is no longer present.
Case 2: Large gap between indoor and outdoor machines and frequent machine protection.
On-site verification: A primary school installed more than 10 sets of 5-hp cabinet machines, two of which often have abnormal protections. After on-site inspection, it was found that the gap between the inside and outside of the two sets of machines was about 8 meters. The connecting pipe has no return bend.
Reason analysis: Because the outer machine is 8 meters higher than the inner machine, the lubricating oil must overcome greater gravity in the cycle to return to the oil. The greater the drop between the inner and outer machines, the more difficult it is to return the oil, and the lack of oil will cause frequent compressor protection or malfunctions .
Treatment method: For machines with a drop of more than 5 meters, an oil return bend must be set at no more than 5 meters apart, and the return bend can be set to "U" or "back" type.
Case 3: Improper installation, the pipeline is folded, and the indoor unit makes noise.
On-site verification: A three-horse cabinet machine was installed in the office of a certain unit, and it has been reported to be squeaking during a certain period of time.
scene Investigation:
A: Observe when the compressor is turned on. The howling sound is emitted after 1 minute after starting the compressor. The sound changes from small to louder, and the sound becomes smaller for about 2 minutes, but the howling sound can still be heard.
B: After investigation, it was found that the position of the suction pipe of the indoor unit connecting pipe was flattened. When the low-pressure pressure dropped to 6-7 kg, the whistling sound disappeared when the low-pressure pressure was balanced at 5.5 kg.
Case 4: The user voltage is unstable.
On-site verification: The newly installed 3-hp cabinet machine has a loud noise after running for 3 minutes, and the fault remains after the compressor is replaced. It was found on the scene that two minutes after the compressor started, the voltage dropped from 198V to 173V. At this time, the compressor began to make a "humming" sound and then stopped.
Reason analysis: The user's power supply voltage is too low and the compressor cannot start normally. It is recommended that the user install a voltage stabilizer.
Case 5: Leakage of refrigerant.
An outlet reported that a 5-hp cabinet machine was installed in a restaurant, and three compressors were replaced after three years of use. A few days ago, they said they did not refrigerate.
On-site verification: On-site inspection, it is found that the compressor does not start, and the resistance of the terminals U, V, W is about 60 ohms, which is normal. The compressor was forced to start, and a humming sound was heard, and the compressor was judged to be stuck.
Reason analysis: There is a lot of oil pollution at the valve of the outdoor unit. Remove the small nozzle nut and find that the small pipe bell mouth is cracked. The analysis is that the nut is fixed too hard during the second maintenance, which causes the bell mouth to twist, causing system refrigerant leakage.
On-site treatment: put the refrigerant, pour out the compressor oil and observe that the oil is dark in color, as shown in the figure below:
Because the compressor oil is close to black, it means that the system is seriously dirty. At the same time, because the liquid storage tank is difficult to clean, the compressor and liquid storage tank are replaced simultaneously, and the system is flushed with nitrogen and refrigerant. Back to normal.
