Dec 28, 2021 
If the refrigerator compressor is broken and can no longer be repaired, you need to buy a new one to replace it. When replacing, you need to follow the correct steps. Then how to change the refrigerator compressor? The following are the detailed steps.
1. Detailed Steps to Replace the Compressor
1.1 Disassembling the Compressor
Take a refrigerator using R600a as refrigerant as an example. The pressure of R600a refrigerant is negative pressure when the system fails. So when the low pressure pipe of the refrigerator has internal leakage, the refrigerator is most likely to be blocked by ice, which causes the compressor burnout.
Before replacing, you need to prepare tools including a refrigerator compressor, screwdriver, micro tube cutter, vise, welding torch, and 8-10 open end wrench.
Step 1. Unplug the power cable of the refrigerator, and use a screwdriver to disassemble the back of the refrigerator under a safe condition. Then you may need to wait about 20 minutes for the refrigerator machine to cool down. There is a lot of hot metal there and it is difficult to handle, so it is worth the wait for a while.
Figure 2: The refrigerator back cover.
Step 2. Use a micro tube cutter to cut the process tube of the refrigerator compressor to release the refrigerant R600a in the refrigerator system. In order to prevent the refrigeration oil from rushing out, please file a seam with a file in the lower part of the end of the process tube first, and slowly release the refrigerant. The process tube is used for filling refrigerant and vacuumizing in production.
Figure 3: The process tube of the compressor.
Step 3. After all the refrigerant R600a in the refrigerator system is released, use a cutter to cut the low-pressure pipe and high-pressure pipe connecting the refrigerator and the compressor. By the way, there is a question about how to judge high-pressure pipe and low-pressure pipe. The thinner tube is a high-pressure tube, and the thicker tube is a low-pressure tube. In addition, the pipes are marked like L--low pressure, and H--high pressure.
Figure 4: The low pressure pipe of the compressor.
Step 4. Open the junction box of the compressor, and unplug the wires connected to the compressor protector and starter. Before unplugging these wires, you can take photos of all the connections between the wires and the compressor. When you install a new compressor, you can use these pictures as a visual aid.
Figure 5: Wires connected to the refrigerator compressor.
Step 5. Use a vise to remove the plates that fix the bottom of the compressor. There are 4 plates in total. If it is fixed with screws, use an 8-10 open-end wrench to remove all four.
Figure 6: Remove the plates that fix the bottom of the compressor.
Step 6. Hold the refrigerator compressor in your hand, slowly lift it upwards, and pull it out to take out the refrigerator compressor.
Step 7. Use sandpaper to clean the 2cm of the high and low pressure pipe heads cut off from the refrigerator.
Figure 7: The heads of the high pressure pipe and low pressure pipe.
Step 8. Clean up the dust inside, and no need to clean up if there is no dust.
Step 9. Install the new compressor into the right position and fix it. Use a vise to insert the polished high and low pressure pipes and pressure gauges into the high and low pressure pipes and process ports of the compressor respectively. Then use a welding torch to weld them firmly and check the tightness of the welded part.
After the compressor is replaced, you can enter the next process: vacuumizing and filling refrigerant.
Figure 8: A new refrigerator compressor.
1.2 Reasons for Vacuumizing before Filling Refrigerant
Before filling refrigerant into the ice machine system, vacuumizing is aiming to remove the air and moisture in the system, and to further check the airtightness of the system under vacuum conditions. If the system is mixed with air and moisture, a series of undesirable consequences will be produced.
Since the adiabatic index of air is greater than that of the refrigerant, the compressor discharge temperature is higher than that of refrigerant gas.
After the air enters the system, the refrigerant condensing pressure will also increase.
Due to the presence of air, the air layer forming on the inner surface of the heat transfer tube of the condenser has the effect of increasing the thermal resistance and reducing the heat dissipation capacity of the condenser.
The interaction between water and refrigerant in the system will produce acidic substances, which will corrode pipes and equipment.
Water is not dissolvable with the refrigerant in the system, and this situation will cause an "ice block" phenomenon at the orifice of the expansion valve. Therefore, the air and moisture in the system must be reduced to a minimum. So the system must be evacuated to a vacuum of 98.7kPa (740mmHg), and make the water boil, evaporate and discharge.
1.3 Vacuumizing Steps
Figure 9: Three-colour tube and meters.
Connect the 90°elbow of the yellow (middle) hose in the manifold pressure gauge to the vacuum pump, connect that of the blue (low pressure) hose to the maintenance valve port of the low pressure pipeline (marked as S or SUC), and connect the red (high-pressure) hose connector to the high-pressure pipeline maintenance valve port (marked as D or DIS).
Open the manifold pressure gauge, open the high and low pressure manual valve, and start the vacuum pump.
When the negative pressure value of the low pressure gauge is higher than 100kPa (750mmHg), stop vacuumizing.
Close the high and low pressure manual valve, and the low pressure side gauge needle shall not rise significantly within 10 minutes. If not, the system can be filled with refrigerant. If there is, a small amount of refrigerant should be charged into the system. Then please look for, and check the leak point and vacuumize again.
1.4 Method for Filling Refrigerant into Refrigerator Compressor
After the system is evacuated, the refrigerant can be filled. Generally, the following methods can be used.
Choose the right refrigerant, which will be mentioned on the compressor label. When beginning to fill the refrigerator with refrigerant, first disconnect the yellow tube from the vacuum pump, and then connect it to the refrigerant bottle and tighten it. Next, open the refrigerant bottle (placing it upright), open the valve core on the meter group to exhaust the air in the yellow tube, and then turn the refrigerant bottle upside down and put it away.
At the same time, open the high and low pressure valve, and add refrigerant to the system. Please close the high and low pressure valve when the specified amount is reached, and put the refrigerant bottle positively.
Take precautions before adding refrigerant because refrigerant is a chemical substance that depletes the ozone layer. If you are in contact with it, which may damage your skin. You also need to strictly follow the instructions on the refrigerant bottle to add refrigerant.
Figure 10: Refrigerant bottles in different colours.
1.5 Checking the Effect of the filling
Please turn on the system first. After a certain period of time (about 5~10min), check whether the high and low pressures of the system are normal. If it is insufficient, slowly open the low-pressure valve in the running state (it is strictly forbidden to open the high-pressure valve at this time), and continue to add an appropriate amount of refrigerant (the cylinder is placed upright). Then close the low-pressure valve, and re-test.
If it is too high, close the cylinder, and slowly open the high-pressure valve. Let it discharge an appropriate amount of refrigerant from the valve core of the meter group (at this time, pay attention to the sprayed refrigerant hurting people), then close the high-pressure valve, and re-test.
Repeat the operations as above until the pressure is normal. Turn off the system, close the refrigerant bottle and the high and low pressure quick connector. The remaining refrigerant in the meter group should be discharged from the valve core of the meter group (at this time, pay attention to the sprayed refrigerant hurting people). Then remove the high and low pressure quick connector (at this time, pay attention to high temperature scalding hands), remove the refrigerant bottle, remove the three-color tube, and keep them properly.
2. Reasons for Refrigerator Compressor Broken
The refrigerator compressor may be broken due to the following reasons.
Due to the lack of oil in the compressor or too much residue in the oil, the rotor holds the shaft causing the motor to burn out.
The wiring of the compressor's starting coil and running coil is wrongly connected.
The aging of the motor winding coil insulation causes a short circuit between turns to burn out the coil.
Too much refrigerant is added to the refrigerator, causing the compressor to run overloaded, and finally the motor winding coil burns out.
Figure 11: Burnt-out compressor coils.
3. Summary
The above text introduces detailed steps for replacing the refrigerator compressor, and some of the reasons that cause the refrigerator compressor to be damaged. It should be noted that before replacing the compressor, it is necessary to find out the cause of the compressor burnout. Otherwise, the compressor may still burn out. The high-pressure pipe of the refrigerator compressor must be cut with a tube cutter, and must not be welded directly with a welding torch. Otherwise it will cause a fire and explosion hazard.
If the damage of the refrigerator compressor is caused by internal leakage, the internal leakage must be dealt with before replacing the compressor. If the compressor of the refrigerator is burned out, the pipes also need to be cleaned.
As a whole, the compressor replacement steps are still relatively complicated. If you are not clear about the replacement steps or feel that it is troublesome to replace it yourself, it is best to seek professional help.
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