Description of 18 Common Faults of Air Conditioning Compressor

1. How do I identify the 3 terminals on the fully enclosed compressor casing?
The resistance between operating terminal (R), starting terminal (S), common terminal (C), and RS is greater than the resistance between SC and RC. The resistance between RS is equal to the resistance between SC and the resistance between RC.
The above rules can be used to distinguish. It should be noted that the electrical and mechanical resistance values for the temperature rise test of the terminals of the three-phase compressor are equal.
2. How to judge the short circuit of compressor motor winding?
Use a multimeter to select a resistance range, and after zero adjustment, measure the resistance values of the compressor motor winding C-R or C-S. If the resistance value of the measured winding is less than the normal value, it can be determined that the winding is short-circuited.
Three-phase compressor:
The resistance value measured twice is infinite, indicating that there is an open circuit in a group of windings;
The three tests were all infinite, indicating that at least two groups of windings were open circuited;
In two of the three measurements, the measured resistance value was significantly lower than that of the other, indicating a short circuit.
3. How to judge whether the compressor motor is connected to the ground due to casing collision?
Use the resistance range of a multimeter. Then, hold one pen tightly against the common point, and place the other pen tightly against the compressor process pipe to expose the metal part, or take a small piece of the paint off the housing plate for measurement. If the resistance value is very small, it can be determined that the winding or internal wiring is grounded against the shell.
4. How to judge whether the compressor motor winding is open circuit?
Adjust the multimeter to the resistance gear, connect the probe to the terminals of any two windings, and measure their resistance. If the winding value is infinite, that is, there is no conduction between the terminals of the two windings, it can be determined that the winding is open circuit.
5. What does the compressor not start to check?
Check whether the compressor overload, pressure switch, and overcurrent protector are tripped or damaged.
Check for an open or poor connection at the indoor temperature sensor and tube temperature sensor
Check whether the relay is engaged, whether the compressor is open or shorted, and whether the compressor capacitance is damaged.
6. What are the reasons why the compressor overheated and stopped shortly after starting?
Insufficient or excessive refrigerant, clogged capillary components, and internal leakage of the four-way valve.
The compressor itself has faults, such as short circuit, open circuit, grounding, etc.
The high pressure pressure is too high, and the pressure relay acts.
Poor ventilation of the condenser or short circuit of air flow, or non-condensable liquid gas mixed in the system.
The ambient temperature of the outdoor unit is too high.
The compressor is stuck in the cylinder or holding the shaft.
7. Performance of low compressor efficiency
Generally, the exhaust pressure decreases, the suction pressure increases, and the temperature of the compressor cylinder head and suction and exhaust cavities is too high.
8. Judgment of compressor losing working ability
First, test whether the intake port has air intake, and then test whether the exhaust port has air exhaust. Use your hand to block the exhaust port. If you feel that the pressure is not very high, or even there is no air exhaust, you can consider that the compressor has lost its working ability.
9. Why is the current of the compressor motor excessive?
The compressor has an inter turn short circuit, but it does not reach the level of blowing the fuse. The "secondary friction" of the compressor destroys the smoothness of the friction surface, resulting in an increase in the power and current of the compressor, but has not yet reached the level of "holding the shaft" or "jamming the cylinder", which prevents the compressor from rotating.
Use a multimeter to check the insulation resistance of the compressor to the ground. Normally, it should be above 2M Ω. If it decreases or approaches zero, it indicates a short circuit. If the insulation resistance to ground is normal, check the resistance values of the starting and operating windings. If there is a short circuit between turns, the operating current increases.
10. Why is it difficult to start the three-phase compressor motor?
The power supply voltage is too low, the compressor motor winding is short-circuited, or the compressor cylinder is stuck.
11. How to eliminate faults such as three-phase compressor motor slowing down, one phase fuse blowing, and one phase current increasing during operation?
It is often caused by a collision between the windings of the compressor motor and the ground. After removing the ground wire, use a test pencil to measure whether the chassis is electrified. If the casing is electrified, rewind the compressor motor winding or replace the compressor.
12. How to eliminate the "chatter" sound generated by the three-phase compressor motor during operation?
The three-phase compressor motor emits a "chatter" during operation, which is caused by serious three-phase imbalance. One phase of the power supply is out of phase, and the three-phase can be restored.
13. How to eliminate reverse rotation of three-phase compressor motor?
It is caused by a wiring error. Arbitrarily exchange two lines in the three phases.
14. Compressor replacement sequence and precautions
R22 is a non combustible gas, but when it comes into direct contact with a high-temperature flame, it can produce toxic gases. Therefore, before welding operations, discharge the refrigerant from the refrigeration system.
R32 is a flammable and explosive refrigerant, and we have repeatedly emphasized the characteristics of this refrigerant. Any R32 refrigeration equipment that involves the maintenance of a refrigeration system and requires replacement of accessories must undergo vacuum pumping before operation! Be careful not to introduce ignition sources!
R410A is low toxic, non flammable, and non explosive. When replacing a compressor, it is necessary to use a dedicated compressor of R410A, and it is absolutely not allowed to use a compressor of R22 to install it. When replacing valve parts, there is a special identification on the valve body of R410A
15. What are the types of air conditioner compressor overload protectors?
External overload protector;
Embedded overload protector.
16. What are the protections for compressors?
Overload protector: mainly used for overcurrent and overheat protection of compressor motors.
Internal protector: mainly used for overcurrent protection of compressor motor.
Thermal relay: mainly used for line overcurrent protection of three-phase compressor motors.
Inverse phase preventer: mainly used for three-phase rotary compressors to prevent the compressor from rotating in the opposite direction or lacking phase energy.
17. What are the common reasons for overload protectors?
The power supply voltage is too low and the symmetry of the three-phase voltage is poor.
The compressor motor operates at low speed for extended periods of time.
The compressor motor operates under low voltage and load for a long time.
The cooling medium path of the compressor motor is blocked.
The ambient temperature for use is too high.
18. What is the liquid hammer of a compressor?
The refrigerant does not completely evaporate in the evaporator, causing the refrigerant to be sucked back by the compressor as wet vapor or liquid, causing a liquid shock of the compressor.