How to Identify a Bad Burnout Compressor in HVACR Systems

How to Identify a Bad Burnout Compressor in HVACR Systems

Table of Contents

  • Introduction
  • How to Measure Compressor Windings
  • Understanding Resistance Readings
  • Checking for Short to Ground
  • Inspecting the Compressor Plug
  • Diagnosing a Burnout Compressor
  • The Effects of a Burnout Compressor
  • Mini-Split Compressor Testing
  • Resources and Additional Information
  • Conclusion

Introduction

In this article, we will discuss how to determine if you have a bad burnout compressor. It is crucial for technicians to accurately confirm a compressor's status before proceeding with repairs. We will guide you through the process of measuring the windings using a multimeter and interpreting the resistance readings. Additionally, we will cover how to check for a short to ground and inspect the compressor plug. We will also explore the effects of a burnout compressor and provide guidance on testing mini-split compressors. Let's dive in!

How to Measure Compressor Windings

To accurately assess the condition of a compressor, you need to measure the windings using a multimeter. Start by ensuring that the power is disconnected from the contactor. Identify the compressor wires and disconnect them. Set your multimeter to measure resistance (ohms) and attach the alligator clips to the appropriate terminals. Measure the resistance between different pairs of wires, such as black and yellow, black and blue, and blue and yellow. These readings will help you identify whether the windings are intact and determine the common, run, and start terminals.

Understanding Resistance Readings

The resistance readings between the compressor windings are essential for diagnosing the compressor's condition. Typically, the lowest resistance reading is between the common and run terminals. The second lowest resistance reading indicates the common and start terminals. By adding the resistance values, you can calculate the total resistance between the start and run terminals. However, it is important to note that resistance readings alone cannot confirm a compressor's functionality. Further testing is required to identify potential issues.

Checking for Short to Ground

A short to ground is a common problem with compressors. To check for a short, find a clean spot on the copper tube brazed into the compressor. Connect one alligator clip to the tube and the other to any of the compressor wires. If the multimeter displays an "OL" or open line reading, it means the compressor is not shorted to ground. Ensure you check the resistance values between pairs of wires first before performing the short to ground test. If you receive excessively high resistance readings or unusual readings, further investigation is necessary.

Inspecting the Compressor Plug

The compressor plug deserves thorough inspection as it can indicate potential issues. Carefully remove the plug, taking precautions to prevent refrigerant leakage. Examine the plug for burn marks, melting, or damage. If the plug appears damaged, consider replacing it with a suitable plug assembly. It is essential to have a properly sealed plug to maintain system integrity. Be cautious while handling the plug and wear safety glasses, as refrigerant leaks can occur.

Diagnosing a Burnout Compressor

A burnout compressor demands immediate attention due to the detrimental effects it can have on the system. If you suspect a burnout compressor, observe the black soot present in the compressor compartment, line set, evaporator coil, and condenser coil. Replacing the outdoor unit alone may not eliminate the residue present throughout the system. Cleaning the line set is feasible, but removing the residue from the evaporator coil is challenging. Keep this in mind during your diagnosis.

The Effects of a Burnout Compressor

When a compressor burns out, the refrigerant continues to circulate, spreading contaminants throughout the system. This circulation can result in the accumulation of black soot in various components. If you replace the compressor, it is crucial to clean the line set thoroughly to prevent contamination from impacting the new compressor and other system components. Be aware of the potential acidity within the system caused by a burnout compressor.

Mini-Split Compressor Testing

Testing a mini-split compressor requires specific considerations, especially for three-phase compressors. The resistance readings between each pair of wires should match. Additionally, all three pairs should read "OL" when tested to ground. Any deviations from these readings indicate a potential issue with the compressor. Use caution when removing the plug, as refrigerant leakage can occur. Take proper safety measures and consider using a compressor lug repair kit if necessary.

Resources and Additional Information

For more information on HVACR troubleshooting and related topics, visit our website at acservicetech.com. We offer a wide range of free resources, including articles, quick tips, Q&A, calculators, quizzes, and more. If you're looking for comprehensive guides, check out our refrigerant charging and service procedures for air conditioning book, available in both physical and eBook formats. For additional resources, visit our English and Spanish eBooks on Apple Bookstore and Google Play. Physical products are also available on Amazon and eBay.

Conclusion

In conclusion, accurately diagnosing a bad burnout compressor is crucial for effective repairs. By measuring the windings, checking for shorts to ground, and inspecting the compressor plug, you can identify potential issues and take appropriate actions. Remember that a burnout compressor can have long-lasting effects on the system, leading to contamination and the spread of black soot. Pay attention to the cleanliness of the line set and consider professional assistance if needed. Follow the necessary safety precautions throughout the diagnosis process.

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