How to Test If a Fridge Compressor Is Working? Explained

The best way to test if a fridge compressor is working is to use a multimeter to measure the resistance of the compressor windings. This will tell you if the compressor is getting power and if the windings are intact. A faulty compressor can cause your fridge to stop cooling or make loud noises. In this article, we will explain how to perform this test step by step, as well as some other ways to troubleshoot your fridge compressor.

What is a Fridge Compressor and How Does It Work?

A fridge compressor is the heart of your refrigerator. It is a pump that compresses the refrigerant gas and circulates it through the evaporator and condenser coils. The refrigerant gas absorbs heat from the inside of the fridge and releases it to the outside, creating a cooling effect. The compressor is controlled by a thermostat that turns it on and off according to the temperature inside the fridge.

The compressor has three main parts: the motor, the pump, and the windings. The motor drives the pump, which compresses the refrigerant gas. The windings are coils of wire that surround the motor and create a magnetic field that makes the motor spin. The windings have different resistance values depending on their function: the start winding, the run winding, and the common winding. The start winding provides a boost of power to start the motor, the run winding maintains the motor speed, and the common winding connects the other two windings.

How to Test the Compressor Windings with a Multimeter

To test the compressor windings, you will need a multimeter, a screwdriver, and a pair of gloves. Make sure to unplug the fridge before you begin and wear gloves to protect yourself from electric shocks. Follow these steps to perform the test:

  1. Locate the compressor at the back or bottom of the fridge. It is usually a black or silver cylinder with wires and tubes attached to it.
  2. Remove the cover of the compressor terminal box. This is a small metal box that houses the wires that connect the compressor to the power source. You may need to unscrew or pry off the cover with a screwdriver.
  3. Identify the three terminals on the compressor. They are usually labeled S, R, and C, corresponding to the start, run, and common windings. If they are not labeled, you can use a wiring diagram of your fridge model to find out which terminal is which.
  4. Set your multimeter to the ohms or resistance setting. This is usually indicated by the symbol Ω. If your multimeter has a range of settings, choose the lowest one that can measure up to 30 ohms.
  5. Touch the probes of the multimeter to any two terminals on the compressor. Note the reading on the display. It should be between 5 and 15 ohms. If it is zero, infinity, or very high, it means that the winding is shorted, open, or damaged.
  6. Repeat the process for the other two pairs of terminals. You should get three readings in total, one for each winding. The start winding should have the highest resistance, the run winding should have the lowest resistance, and the common winding should have a resistance value between the other two.
  7. Add up the resistance values of the start and run windings. The sum should be equal to or slightly higher than the resistance value of the common winding. For example, if the start winding has a resistance of 10 ohms, the run winding has a resistance of 5 ohms, and the common winding has a resistance of 14 ohms, the sum is 15 ohms, which is close to the common winding value. This means that the windings are in good condition. If the sum is significantly lower or higher than the common winding value, it means that the windings are faulty or mismatched.
  8. Replace the cover of the compressor terminal box and plug the fridge back in.
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Other Ways to Troubleshoot Your Fridge Compressor

Testing the compressor windings with a multimeter is the most reliable way to determine if your fridge compressor is working, but there are some other signs and symptoms that can indicate a problem with the compressor. Here are some of them:

  • The fridge is not cooling or is too warm. This could mean that the compressor is not running or is not pumping enough refrigerant. Check the thermostat setting, the condenser coils, and the evaporator fan to make sure they are working properly. If they are, the compressor may be the culprit.
  • The fridge is making loud or unusual noises. This could mean that the compressor is overheating, vibrating, or rubbing against something. Listen to the compressor and see if you can identify the source of the noise. It could be a loose or broken part, a worn-out bearing, or a faulty relay or capacitor. You may need to replace or repair the part or the compressor itself.
  • The compressor is hot to the touch. This could mean that the compressor is working too hard or is not getting enough ventilation. Make sure that there is enough space around the fridge and that the condenser coils are clean and free of dust and debris. If the compressor is still hot, it may be defective or overloaded.
  • The compressor is cycling on and off frequently or not at all. This could mean that the compressor is having trouble maintaining the desired temperature or is not getting enough power. Check the voltage and the current of the power source and make sure they are within the specifications of the compressor. If they are, the compressor may have a faulty thermostat, relay, or capacitor.
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Conclusion

A fridge compressor is an essential component of your refrigerator that keeps your food and drinks cold and fresh. If you suspect that your fridge compressor is not working, you can test it with a multimeter to measure the resistance of the compressor windings. This will tell you if the compressor is getting power and if the windings are intact. You can also look for other signs and symptoms that can indicate a problem with the compressor, such as poor cooling, loud noises, overheating, or irregular cycling. If you find any issues with your compressor, you may need to contact a professional technician to fix or replace it. We hope this article has helped you learn how to test if a fridge compressor is working and what to do if it is not.