AC Tripping Breaker? How to Fix Electrical Overloads Fast
Breaker trips are your system’s cry for help. Learn what causes overloads, which checks you can make safely, and how Efficiency Heating & Cooling resolves stubborn breaker issues for Portland homeowners.
Serving Multnomah, Washington, and Clackamas counties with licensed HVAC technicians and electrical partners.
Owner & Lead HVAC Technician
Quick Answer
Breaker Keeps Tripping? Follow These Steps
Most AC breaker trips stem from preventable issues: failed capacitors, dirty coils, loose wires, or aging breakers. Reset the breaker once after performing the checklist below. If it trips again, leave it off — repeated attempts can damage your equipment and wiring.
Turn the thermostat to OFF before resetting any breakers.
Locate the dedicated AC breaker in the main electrical panel and reset it once.
Inspect the outdoor disconnect box for blown cartridge fuses.
Remove debris and cottonwood fluff from around the condenser to restore airflow.
Replace the indoor air filter to reduce system static pressure.
If the breaker trips again immediately, leave it OFF and call a licensed HVAC/electrical professional.
Top 10 Reasons AC Breakers Trip in Portland
Breakers protect your home, so when they trip it means the AC drew more electrical current than the circuit could supply. In Portland’s damp climate and tree-filled neighborhoods, electrical components age faster, while seasonal pollen clogs coils. Understanding the root causes lets you respond quickly and avoid costly outages during July heat waves or wildfire smoke events when you need cooling most.
Shorted Compressor Windings
When compressor windings short to ground or to each other, amperage spikes beyond the breaker rating. This is common in aging compressors or systems exposed to moisture intrusion during winter.
- •Signs: Breaker trips immediately when the compressor attempts to start, sometimes accompanied by a loud buzz.
- •Diagnostic tools: Megohmmeter testing, amp draw measurements, visual inspection for burn marks.
- •Solution: Compressor replacement or full system upgrade. Average cost $1,500-$2,500 for compressor-only swap.
Failed Start or Run Capacitor
Weak capacitors force the compressor or fan motor to draw high amps as they struggle to start, tripping breakers within seconds.
- •Capacitors degrade faster in Portland homes with frequent power fluctuations or systems that sit idle in damp environments.
- •Replacement cost: $150-$400 with testing to ensure other components were not damaged.
- •Prevention: Annual maintenance to test capacitance and install surge protection.
Dirty Condenser Coils and Restricted Airflow
Overheated compressors pull more current. Cottonwood fluff, leaves, and pet hair block coils, causing head pressure to soar. The breaker trips to protect wiring.
- •DIY: With power off, rinse coils from the inside out using a garden hose. Maintain 24 inches of clearance.
- •Professional cleaning: $100-$200 with coil-safe detergents and fin straightening.
Loose or Corroded Electrical Connections
Loose lugs in the disconnect, corroded wire nuts, or rodent damage creates resistance that overheats conductors and breakers.
- •Common in crawlspace or outdoor conduit exposed to rain and river moisture.
- •Repair requires tightening/rewiring by a licensed technician. Costs vary $150-$500.
Breaker Sized Incorrectly or Aged Out
Older panels may have breakers that weaken over time or were undersized during installation. Portland homes built before the 1990s sometimes use tandem breakers or panels nearing capacity.
- •Solution: Replace breaker with proper OEM-rated unit. If panel is obsolete, an electrical panel upgrade ($1,500-$3,000) may be required.
- •Always match breaker size to manufacturer specifications on the AC nameplate.
Low Refrigerant Charge Causing Freeze-Ups
A frozen coil blocks airflow. When the ice melts, water drips onto the blower motor or electrical components, causing short circuits and breaker trips.
- •Symptoms: Ice on lineset, water around furnace, long runtimes.
- •Professional repairs include leak detection and recharge ($400-$1,500).
Bad Contactor or Relay
A pitted contactor can weld closed, keeping the compressor running even when the thermostat is satisfied. Continuous running overheats the motor and trips the breaker.
- •Replacement contactors cost $150-$350.
- •Technicians also inspect low-voltage wires for shorts that cause relays to stick.
Shared Circuit or Added Electrical Load
Window ACs, EV chargers, or hot tubs added to a home without panel upgrades may share a leg with the central AC circuit. Combined load exceeds breaker capacity.
- •Solution: Dedicated circuits for high-load appliances and possible service panel upgrade.
- •We coordinate with trusted electricians for whole-home load calculations.
Blower Motor Overamps
A failing indoor blower motor or clogged filter causes the furnace breaker to trip, especially if the same breaker feeds both blower and outdoor unit.
- •Symptoms: Breaker trips during both heating and cooling seasons.
- •Repairs: Motor replacement ($450-$1,100) or capacitor swap ($140-$320).
Storm Surges and Lightning
Summer thunderstorms and PNW windstorms cause voltage spikes. Even without direct lightning hits, utility surges trip breakers and damage control boards.
- •Install whole-home surge protection ($400-$900) and individual HVAC surge suppressors ($150-$250).
- •Always schedule post-storm inspections if breakers trip repeatedly.
Protect Your System from Future Trips
Call the Pros When:
Breaker trips again immediately after reset.
You hear buzzing or smell burning plastic at the outdoor unit.
Lights dim when the AC starts, indicating voltage drop in the panel.
The breaker is hot to the touch or shows signs of charring.
AC Breaker FAQs for Portland Homeowners
Keep Your Cooling System Running Safely
Efficiency Heating & Cooling repairs breaker trips fast, tests every electrical component, and provides clear recommendations whether you need a simple part or a system upgrade. Restore peace of mind before the next heat wave.