The 4 Senses of Electrical troubleshooting

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 Start by opening the panel and performing a visual inspection:

• No indicator lights?
   
  • Check main power
     
  • Verify control transformer or 24 VDC power supply
     
  • Look for “OK” indicator on power supply
     
• Lights are on?
   
  • Check for blown fuse indicators
     
  • Look for flashing red LEDs (consult manuals)
     
• Verify:
   
  • PLC I/O light is green
     
  • No carbon buildup around terminals (overheating)
     
  • No cracked, melted, or discolored components
     
• Watch for movement:
   
  • Wires moving under load = excessive current → shut down immediately
     
• Environmental checks:
   
  • Debris, moisture, or rodent damage at panel bottom
     
  • Improperly mounted panel A/C units (condensation risk)
     
• Compare with a known-good system when available:
   
  • Indicator lights
     
  • Sensor status
     
  • Panel conditions
     

⚠️ Never touch energized components. Lock out power first.
✔️ Thermal imaging is strongly recommended over physical touch.

• Motors:
   
  • Standard: < 140°F
     
  • Washdown motors: ~20°F hotter
     
  • Too hot to touch = likely overload or failure
     
• Thermal scan targets:
   
  • Components over 140°F
     
  • Imbalances (e.g., one phase hotter than others)
     
• Watch for:
   
  • Uneven heating
     
  • Excessive vibration or humming (insulation breakdown at 60 Hz)