Turn off power to the AC unit at the breaker
Verify power is off with a voltage tester
Remove the access panel
Locate the capacitor
Take a photo of the wire connections
Discharge the capacitor using a resistor or insulated screwdriver
Disconnect the wires from the capacitor terminals
Set the multimeter to capacitance mode if available
Place the probes on the capacitor terminals
Read the capacitance value on the meter
Compare the reading to the capacitor’s rated value
Replace the capacitor if the reading is far below the rating or shows no reading
If capacitance mode is not available, set the multimeter to resistance mode
Touch the probes to the terminals
Watch for the reading to start low and then climb toward infinity
Reverse the probes and repeat the test
Replace the capacitor if the reading stays at zero, stays at infinity, or does not change
Reconnect the wires exactly as they were
Reinstall the access panel
Restore power to the AC unit