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AC capacitor failure can happen from time to time, even to the best air conditioners. Because of this, capacitors need to be tested every few years or if you find your unit running weaker than normal. An indication of this can be the lights dimming when the air conditioner comes on. You don’t want to react and scrap your air conditioner, however. This article will show you how to test an air conditioner capacitor with a digital multimeter.
Alternatively, if your unit is having other performance problems, check out our article on how to straighten air conditioner fins. Or to check whether your compressor is going bad, read up on how to test an air conditioner compressor.
To check if your capacitor is blown, you can check it visually to see if it looks like a pop can with a pushed-up top.
The AC capacitor is a small silver cylindrical object with three wires connected to the top. It stores energy and delivers a large power boost to the motor, which kicks off the cooling cycle.
Unplug the AC unit, or go to the breaker that powers the AC unit and turn it off.
Make sure to disconnect the three wires before touching the capacitor with your bare hands to avoid injury.
Will an AC run with a bad capacitor
If you have a bad AC capacitor, the unit will likely stop running, and you’ll hear a humming sound coming from it.
How long do AC capacitors usually last?
If kept under suitable conditions, AC capacitors can last for 20 years.
What causes AC capacitors to go bad?
AC capacitors often go bad from power surges, overheating, and short circuits.
STAT: The acceptable ohm range is usually labeled on the capacitor. If the capacitor tells you “50 ±5%,” the acceptable range is 47.5 to 52.5 F. (source)