Breaker Keeps Tripping on AC Unit

Quick answer

If your AC unit’s breaker keeps tripping, first turn off the AC and unplug it. Check the circuit breaker for damage or overheating, and ensure the unit is properly grounded. If the problem persists, inspect the capacitor, contactor, and wiring for faults.

Confirm the symptom

• Circuit breaker trips repeatedly when AC is on
• AC unit powers off suddenly
• Breaker trips even after resetting
• No other appliances on the circuit are causing the trip
• AC unit is properly plugged in and grounded

Tools and prep

• Non-contact voltage tester
• Screwdriver set
• Infrared thermometer
• Multimeter
• Wire brush
• Shop vacuum
• Safety gloves and goggles

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Prep & safety

• Turn off the AC unit and unplug it from the power source.
• Switch off the circuit breaker to the AC unit before inspecting any components.
• Wear safety gloves and goggles to protect against electrical hazards.
• Ensure the area around the AC unit is dry and free from moisture.

Step-by-step troubleshooting

1. Check the Circuit Breaker
   Do: Inspect the circuit breaker for signs of damage, overheating, or burning.
   Observe: Damaged or overheated breaker.
   Means: Faulty breaker or overloaded circuit.
   Next: Replace the breaker or consult an electrician if it’s damaged.
2. Test the Capacitor
   Do: Use a multimeter to test the capacitor for proper capacitance and voltage.
   Observe: Capacitor shows low capacitance or no charge.
   Means: Failed capacitor causing motor overload.
   Next: Replace the capacitor with a matching µF and voltage rating.
3. Inspect the Contactor
   Do: Check the contactor for worn contacts or signs of arcing.
   Observe: Pitted or burnt contactor.
   Means: Faulty contactor causing electrical issues.
   Next: Replace the contactor if damaged.
4. Check for Wiring Issues
   Do: Use a wire brush and shop vacuum to clean terminals and inspect for loose or damaged wires.
   Observe: Loose, frayed, or corroded wires.
   Means: Poor electrical connections causing tripping.
   Next: Tighten or replace damaged wiring.
5. Test the Motor
   Do: Use a multimeter to check the motor windings for continuity.
   Observe: No continuity or high resistance in motor windings.
   Means: Faulty motor causing overload.
   Next: Replace the motor if necessary.
6. Check for Ground Faults
   Do: Use an infrared thermometer to check for hot spots on the unit.
   Observe: Abnormally hot components or areas.
   Means: Possible ground fault or short circuit.
   Next: Consult an electrician for further inspection.

Common causes

Parts you might need

When replacing parts, ensure compatibility with your AC unit’s specifications.

• Circuit breaker: match amperage and voltage ratings.
• Run capacitor: match µF and voltage printed on the old capacitor.
• Contactor: match terminal size and voltage rating.
• Wire connectors: match wire gauge and type.
• Compressor motor: match model number and electrical specifications.

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Always refer to the AC unit’s manual for exact part specifications.

When to call a professional

• The breaker trips immediately after resetting without any load.
• You detect a burning smell or visible damage to electrical components.
• You’re unable to identify the cause after following the troubleshooting steps.
• The AC unit is under warranty and you don’t want to risk voiding it.
• There’s a risk of electrical shock or fire due to unsafe conditions.

FAQ