{ "@context": "https://schema.org", "@type": "HowTo", "name": "How to Troubleshoot Blue Cold Condensing Unit - Compressor starts, but relay does not open", "description": "A field engineer's diagnostic guide to identifying causes and resolving Condensing Unit - Compressor starts, but relay does not open 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-starts-but-relay-does-not-open#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-starts-but-relay-does-not-open#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 starts, but relay does not open

Symptoms

The compressor starts but the replay does not open

Likely Cause
  1. Electrical connections incorrect
  2. Low voltage at compressor
  3. Relay locked closed
  4. Excessive discharge pressure
  5. Electric motor - winding interrupted or in short circuit
Remedy‍
  1. Check the electric circuit
  2. Find and remove the cause
  3. Find and remove the cause
  4. Find the cause and replace the relay if necessary
  5. Replace the compressor or get it repaired

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