Main faults and causes analysis of 01 compressor

1. Locked rotation (stuck): The compressor does not move and makes a "buzzing" sound;

Foreign matter enters, and moving parts such as crankshaft, piston and cylinder are stuck;

The pressure on the high and low pressure sides is unbalanced;

Motor burning;

Voltage is too low;

Compressor is short of oil or overloaded, and mechanical parts are severely ground;

Oil deterioration and severe grinding of mechanical parts;

When heating at low temperature, the compressor temperature is too low;

The compressor capacitor is damaged or attenuated;

Poor clearance between stator and rotor;

2. The compressor can operate, but the exhaust pressure is low:

The compressor sucks liquid;

Condenser failure;

Protector action;

Pipeline resistance is high.

3. The compressor can operate, but it stops due to the increasing current:

Protector action;

Inspiratory pressure is too high;

The mechanical part of the compressor is damaged;

4, compressor overcurrent:

Failure of two devices;

The refrigeration system is blocked;

Overload operation (refrigerant quantity, voltage);

Fan motor speed (capacitance attenuation, fan failure);

Frequency converter should pay special attention to the fault of electric control.

The three cameras are running out of phase, and the winding is burned.

When using an external overload protector, use a multimeter to measure whether the overload protector is on, and it is on normally.

5, loud noise:

When the compressor starts, the sound will be louder within 3 to 5 minutes due to the instability of the system;

Pipeline vibration sound, motor and blade sound, sheet metal resonance sound;

When air is mixed in the system, there will be air flow sound;

When there are impurities or copper chips in the system, metal will hit the valve plate;

Poor clearance between stator and rotor;

Lack of refrigeration oil;

Liquid refrigerant enters the compressor to generate liquid compression;

6, valve plate is bad (no suction and exhaust capacity, high and low pressure cross gas):

The valve plate has a large gap and is stuck (rotor type);

Crankshaft broken, no rotation;

Spring break;

The compressor is short of oil and the valve plate is excessively worn;

Foreign matter enters the compressor cylinder;

Four-way valve cross gas;

Lack of refrigerant;

Three-phase power supply, the reverse phase of power supply will cause the compressor to reverse;

The water content exceeds the standard, resulting in ice blocking.

7, winding current is big:

Whether other parts of the system (mainly motors and electronic controls) work normally;

Stator burning loss (coil short circuit, overload, open-phase operation, refrigerant leakage);

Too much refrigerant charge will lead to high power;

Whether the system may be blocked, resulting in high pressure and low pressure;

Whether the capacitance is normal;

The ambient temperature is too high;

02 Steps and points for attention in replacing compressor

1. Refrigerant discharge: Pay attention to the ventilation of the working environment, and the refrigerant discharge speed should not be too fast, so as to avoid frostbite of personnel by refrigerant; The speed of discharging refrigerant should not be too fast, so as to avoid the refrigeration oil in the compressor being discharged with the refrigerant. Once the compressor is in good condition through subsequent inspection, the lack of refrigeration oil will affect the normal use. Pay attention to the color of the sprayed refrigerant. If the sprayed refrigerant is white or colorless, the internal cleanliness of the system is high. The compressor may not be damaged. Be sure to operate carefully!

2. Dismantle the suction and exhaust pipe: nitrogen charging operation to avoid the generation of scale inside the system, and pay attention to whether there are impurities and foreign bodies on the inner wall of the copper pipe.

3. No-load operation: Before the old compressor is dismantled, the operation time should not exceed 5 seconds under the condition that the suction and exhaust pipes are all open. [This article comes from WeChat official account, an encyclopedia of refrigeration] to judge whether the compressor is blocked or not, and whether there is suction and exhaust. Test whether the compressor has the feeling that you can approach the exhaust port with your fingers; Old compressors with poor insulation and high operating current may leak electricity and cannot be tested in this way.

4. Take down and dispose of the old compressor: the old compressor must seal the suction and exhaust ports within 15 minutes; Must ensure that the old compressor code and machine bar code are clear;

5. Cleaning system: The cleaning solution requires high oil solubility and is easy to volatilize, so R11; is recommended; It is necessary to ensure the cleanliness of the nozzle at the welding place.

6. Replace with a new compressor: in principle, it is required to use the original model and brand compressor; if it cannot be met, the capacity of the new compressor must be consistent with that of the old compressor; Scroll compressor and rotary compressor cannot be interchanged; Single-phase compressor and three-phase compressor cannot be interchanged; To pull out the rubber plug of the compressor, the exhaust pipe must be followed by the suction pipe; During the maintenance process, it is necessary to ensure that the lubricating oil cannot contact the rubber feet of the compressor to avoid deterioration of the rubber feet.

7. Welding the new compressor: nitrogen must be filled for welding, and the nitrogen must reach the welding position; It is advisable to preheat the copper tube until it turns pink; Covered electrode must be melted by the temperature of the copper tube, not directly by the flame.