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"Common Signs of a Faulty AC Compressor and How to Address Them"

Writer's picture: shahid yousuffshahid yousuff
Sep 8, 20243 min read

1. Check for Cooling Issues

  • Set the thermostat to a lower temperature than the room and see if the air coming from the vents is cool.

  • If the AC is blowing warm air.

2. Unusual Noises

  • Turn the AC on and listen for any strange noises coming from the outdoor unit

    • Rattling or banging: This could indicate loose or broken components inside the compressor.

    • Hissing or bubbling: May indicate refrigerant leaks.

    • Buzzing or humming: A sign that the compressor is trying to start but failing.

    • Clicking: Could suggest the compressor is struggling to turn on.

3. Inspect for Refrigerant Leaks

  • Refrigerant leaks can cause the compressor to malfunction or overheat.

  • Signs of refrigerant issues include:

    • Ice buildup on the evaporator coil.

    • Hissing sounds from the outdoor unit.

    • Oily residue around the compressor.

4. Check for Electrical Issues

  • If the compressor isn’t turning on, check for any tripped circuit breakers or blown fuses in the breaker panel.

  • Use a multimeter to test the capacitor (often located near the compressor). A bad capacitor can prevent the compressor from starting.

Steps to Test with a Multimeter:

  • Turn off the power to the AC unit at the breaker.

  • Set the multimeter to the ohms setting.

  • Test for continuity across the compressor terminals (common, start, and run).

  • If you find an open circuit or extremely high resistance, the compressor is likely burned out.

5. Test the Compressor for Grounding

  • A compressor that has shorted to the ground will trip breakers and prevent the system from working.

  • Use a multimeter to check for continuity between the compressor terminal and the metal casing.

    • If there’s continuity, the compressor is grounded and will need to be replaced.

6. Check for High Energy Consumption

  • If the compressor is failing, it may cause the AC system to run inefficiently, leading to increased energy consumption.

  • Compare your energy bills from previous months to see if there's a noticeable increase in usage.

7. Look for Hard Start or No Start

  • A hard start happens when the compressor struggles to turn on and may take multiple tries. This could indicate wear or a bad capacitor.

  • If the compressor fails to start at all, it may be due to:

    • Burned-out motor: The compressor motor may be damaged, requiring a replacement.

    • Bad capacitor: This part is responsible for helping the compressor start.

    • HP / LP Trips: If compressor Turns ON & OFF Continuously. HP / LP Switch might be defective.

8. Inspect the Condenser Coils

  • Dirty or clogged condenser coils can cause the compressor to overheat and fail prematurely.

  • Make sure the condenser coils are clean and free of debris, which allows the compressor to work efficiently.

9. Compressor Overheating

  • Compressors that are overheating will shut down to protect themselves. Check the unit for signs of excessive heat.

  • Overheating may be due to refrigerant issues, clogged condenser coils, or electrical faults.


Summary:

  • Cooling issues and warm air could indicate compressor failure.

  • Listen for strange noises (buzzing, rattling, or hissing).

  • Inspect for refrigerant leaks or check electrical connections.

  • Use a multimeter to test for continuity and grounding issues.

  • Check the compressor fan, condenser coils, and capacitor.

  • If the problem persists, contact a professional HVAC technician for a full diagnostic.

  • Check for HP/LP Switch.

Following these steps can help you determine if your AC unit's compressor is faulty and whether it needs repair or replacement.


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