Bench or under load test.
Furnace blower capacitor test.
Decide if under load or bench testing is best.
Do not do an under load test on blower capacitors due to the risk of the meter leads around a spinning blower wheel.
If you re concerned that your furnace capacitor isn t operating properly you can test it by following a few simple steps.
If the system is not running then a bench test will be the best bet.
A furnace usually uses a run capacitor to maintain a relatively constant voltage supply to the blower motor.
Set a voltmeter to the x1 setting.
Remove the wires from the terminal and discharge the capacitor using the instructions included with your furnace.
Remove the blower housing inside the furnace to access the capacitor.