Turn off power to the AC unit at the breaker and disconnect
Verify power is off with a multimeter
Remove the access panel
Locate the capacitor
Inspect the capacitor for bulging, leaking, or corrosion
Take a photo of the wire connections
Discharge the capacitor safely with an insulated resistor or insulated screwdriver rated for the task
Set the multimeter to capacitance mode
Disconnect the capacitor wires
Measure the capacitor terminals
Compare the reading to the rating printed on the capacitor
Check if the reading is within the capacitor’s tolerance range
If your multimeter does not have capacitance mode, use the ohms test
Place the meter leads on the terminals and observe the needle or display movement
Replace the capacitor if the reading is out of range or if it shows no change
Reconnect the wires exactly as they were
Reinstall the access panel
Restore power and test the AC unit