**The box is most likely a mechanical defrost timer, if it’s mounted to the fridge’s frame beside the compressor.** Without a photo or the component’s label, that identification is tentative. “ABS” identifies the plastic used for the cover, not the device inside.

A mechanical timer uses a small motor and gears to periodically switch the refrigerator from cooling to defrosting. Your description—rapid ticking while cooling still works—suggests either **a noisy timer mechanism or a loose cover vibrating with the compressor**. Feeling vibration in the cover alone doesn’t distinguish those causes.

A compressor start relay is another possibility, especially if the box attaches directly to the compressor’s electrical terminals. However, failed-start clicking usually accompanies interrupted compressor operation and poor cooling; your steady four-clicks-per-second sound is less typical of that fault. [GE’s clicking-noise guidance](https://repair.geappliances.com/resources/faq/article/why-does-my-fridge-keep-clicking-on-and-off)

To investigate:

- **Unplug the fridge before removing the cover.** The enclosure may contain mains-voltage connections.
- Check for loose mounting screws or a cover touching nearby metal or tubing. The Y-shaped screws likely require a tri-wing bit.
- Read the label on the component inside and use that, along with the full refrigerator model number, to confirm its identity.
- If the timer itself is making the noise, replace the complete timer with a confirmed compatible part. If the housing is rattling, correct its mounting.

Don’t bypass the timer, leave its electrical cover off, or pack cardboard inside it. A photo showing the box and how it mounts would help distinguish the timer from the compressor’s starting components.