Day & Night Electrical Overload / Short Circuit

Breaker for outdoor unit trips repeatedly when AC starts

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Shorted compressor windings, Shorted outdoor fan motor, Shorted wiring to ground, Oversized or undersized breaker relative to unit MCA/MOP

How to Fix / Troubleshooting

Safety first: Do not keep resetting a tripping breaker. Turn OFF the breaker and outdoor disconnect and leave them OFF until the fault is found.

  • Step 1 – Visual inspection: Look for burnt wires, melted insulation, or signs of arcing in the outdoor control compartment.
  • Step 2 – Fan motor check: Disconnect fan motor leads (with power OFF) and see if the breaker still trips when the unit is started by a qualified person. This helps isolate the fault.
  • Step 3 – Compare breaker size: Verify the breaker size matches the Minimum Circuit Ampacity (MCA) and Maximum Overcurrent Protection (MOP) on the Day & Night nameplate.
  • Professional diagnostics: A technician should perform megohm and continuity tests on the compressor and fan motor to locate shorts.
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Repair Difficulty

Professional Required 5/5

Required Part

Compressor or Outdoor Fan Motor
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