AC hums and trips

2016 class A, two 13,500 BTU rooftop ACs. 50A pedestal

Customer says: The AC fan blows but it never gets cold. Sometimes it buzzes and the breaker trips.

Tests you can run

• Check the filter
• Voltage at the unit when the compressor tries to start
• Discharge and test the run capacitor (label 45/5 µF)
• Clamp amps on start
• Pedestal voltage

Repair options

The lesson behind this case

• Rooftop AC

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

See it in 3D

• Rooftop AC 3D wiring model

On the job

• Air conditioner
• Thermostat
• Heat pump / heat strip