{ "@context": "https://schema.org", "@type": "HowTo", "name": "How to Troubleshoot Blue Cold Condensing Unit - Compressor did not start but make humming sound", "description": "A field engineer's diagnostic guide to identifying causes and resolving Condensing Unit - Compressor did not start but make humming sound in commercial refrigeration systems.", "totalTime": "PT30M", "estimatedCost": { "@type": "MonetaryAmount", "currency": "USD", "value": "0" }, "step": [ { "@type": "HowToStep", "url": "https://www.bluecoldref.com/troubleshooting/[item-slug]#step1", "name": "Isolate Power & Confirm Safety", "text": "Before touching any electrical panels or mechanical valves, ensure the system is safely isolated following standard Lockout-Tagout (LOTO) protocols." }, { "@type": "HowToStep", "url": "https://www.bluecoldref.com/troubleshooting/compressor-did-not-start-but-make-humming-sound#step2", "name": "Check Ambient and System Pressures", "text": "Attach calibrated manifold gauges to the suction and discharge service valves to verify if the physical system pressures align with electronic controller readings." }, { "@type": "HowToStep", "url": "https://www.bluecoldref.com/troubleshooting/compressor-did-not-start-but-make-humming-sound#step3", "name": "Inspect Condensing Unit for Malfunctions", "text": "Examine the designated component for obvious signs of failure, such as restricted airflow, clogged filter driers, or loose electrical contactor wiring." } ] }

Trouble Shooting

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Condensing Unit - Compressor did not start but make humming sound

Symptoms

The compressor will not start (it makes a humming sound) and the thermal circuit breaker intervenes

Likely Cause
  1. Electrical Connections incorrect
  2. Low voltage at compressor
  3. Faulty start capacitor
  4. The relay does not close
  5. Electric motor - winding interrupted or in short circuit
Remedy‍
  1. Make the connections again
  2. Find and remove the cause
  3. Find the cause and replace the capacitor
  4. Find the cause and replace the replay if necessary
  5. Replace the compressor or get it repaired

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