What does an ac capacitor do?

The AC capacitor (air conditioner capacitor) is like a "backup battery" or "booster" in your air conditioner. Although it's small, usually just a small silver metal can, your air conditioner wouldn't be able to run without it.

1. It's the "powerful pusher" during startup.

There are two big components in the outdoor unit of an air conditioner: the compressor and the fan. These two components require a lot of power to start, and the ordinary household current is often not enough to "pull" them.
Instantaneous burst: The function of the AC capacitor is to release the stored electrical energy in a powerful surge at the moment of startup, giving the motor a huge "initial momentum."
For example: It's like pushing a parked heavy truck; the most difficult part is getting it started. The capacitor is like the person who gives you a strong push from behind. Once the truck starts moving, its job is largely done.

2. It's the "voltage regulator" during operation.

After the air conditioner starts running smoothly, it doesn't completely rest. At this point, its role changes to that of a run capacitor.
Maintaining balance: The current sometimes fluctuates during transmission. The capacitor acts as a buffer, making the current entering the compressor more stable.
Energy saving and noise reduction: With its regulation, the motor rotates more smoothly, without sudden changes in speed, which not only saves energy but also reduces the noise caused by unstable current.

3. It determines the direction of the motor's rotation.

You might not have thought about why the air conditioner fan always blows in one direction, instead of rotating randomly?
Guiding role: The AC capacitor guides the motor's rotation direction by changing the "rhythm" of the current entering the motor. If the capacitor is completely broken, you might find that the fan is rotating, but it's rotating in the wrong direction, or just oscillating in place.

4. It's the "protector" of the air conditioner.

If the current directly impacts the motor, or the motor struggles to start, it will quickly burn out due to overheating.
Sacrificing itself to protect the expensive parts: Compared to the compressor, which costs several thousand yuan, the AC capacitor is a relatively inexpensive part. By "absorbing" and "releasing" electrical energy, it relieves the pressure on the motor. Often, when an air conditioner fails to cool in the summer, it's because the capacitor has "taken the hit" for the compressor and burned out first.