How to Test a Capacitor for a Window AC

Your window air conditioner requires a lot of power to run -- so much that the power coming from your wall is not enough to kick off certain energy-heavy functions. The capacitor of your window air conditioner is responsible for storing excess energy that is used to start the air conditioner. When the capacitor isn't functioning properly, the unit might not start or might run erratically. You can test the capacitor using a multitester, a handheld device used to test electrical current.

Screwdriver
Alligator clips
Capacitor

Instructions

- 1
  Unplug the air conditioner from the wall.
- 2
  Remove the screws holding the faceplate onto the window air conditioner.
- 3
  Pull the faceplate off the air conditioner.
- 4
  Locate the capacitor. It looks like a battery and is near the motor.
- 5
  Attach one end of an alligator clip to the edge of the capacitor and the other end to the metal portion of a rubber-handled screwdriver. Touch the metal part of the screwdriver to the two terminals on top of the capacitor. This removes all the charge and prevents shocks.
- 6
  Set your mulitester to the RX1 setting. Touch the probes together to zero out the tester.
- 7
  Unscrew the wires from the terminals of the capacitor.
- 8
  Touch the red lead of the multitester to the left terminal and the black probe to the right. The needle should read infinity after having a slight spike in voltage. Switch the probes and do the same. It should read infinity after a larger spike. If not, the capacitor is bad.

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