Breaker trips when the AC starts

2016 fifth wheel, 15,000 BTU rooftop AC, 50A service. 50A pedestal

Customer says: The bedroom AC trips its breaker a couple seconds after it tries to start. The living room AC is fine.

20 A breaker for the bedroom AC trips every time. Resetting it doesn't help.

Tests you can run

• Voltage at the panel on the bedroom AC leg
• Discharge and test the run capacitor
• Compressor windings: C to R, C to S, and each to the case
• Run fan only from the thermostat
• Clamp amps on the compressor lead during a start attempt
• Swap in a new 20 A breaker
• Install a hard-start kit
• Hold the breaker in with tape to see if it clears

Repair options

The lesson behind this case

• Compressor windings and the breaker

Keep going on air conditioning

Learn it

• Rooftop AC
• Capacitors
• Airflow and coils
• Thermostats and AC control boards
• Heat pumps and heat strips

Prove it

• AC hums and trips
• AC runs but barely cools
• AC ices up and barely blows
• AC kicks off on hot afternoons
• AC does nothing, thermostat is blank

See it in 3D

• Rooftop AC 3D wiring model

On the job

• Air conditioner
• Thermostat
• Heat pump / heat strip