In this guide
TL;DR: A countertop ice maker may fit under upper cabinets without being suitable for an enclosed cabinet. Check the exact model's installation rules, ventilation gaps and access for filling, draining and cleaning. Some GE Opal guidance allows cabinet placement with conditions; another machine may need a different arrangement.
Under an upper cabinet and inside a cabinet are different choices
An upper cabinet above an open countertop leaves the ice maker exposed to the room. A compartment with a door, side panels and a back surrounds it. Measure the space you actually plan to use before deciding that a machine fits.
GE's Opal installation guidance allows placement inside a cabinet with at least 3 inches of clearance at the rear and sides. It also warns that higher temperatures inside an enclosed cabinet reduce ice production. The same page says to measure the gap from the countertop to the underside of an overhead cabinet.
That is an Opal support example, not a universal approval for countertop machines. Use the installation instructions for your exact model and revision. A product's height alone does not establish ventilation clearance or permission to enclose it.
Read the gap requirement before choosing the spot
GE Opal: cabinet permission comes with airflow conditions
The cited GE page requires an indoor location and an upright, level surface that can support the machine filled with water. Keep it away from ovens, cooktops and direct sun. Leave the required air space open rather than using it for bottles or other stored items.
Newair AI-100SS: a different gap applies
The AI-100SS English manual, version 1.1, calls for at least 5 inches between the machine's rear and sides and the wall. It also requires a level location away from sunlight and heat sources. This manual's number cannot be replaced with the Opal example's 3 inches.
Use the AI-100SS manual's exclusive grounded outlet; do not remove its ground prong. Ask a qualified electrician about an unsuitable outlet or cord route.
Leave room to do the water-care work
Ventilation is only part of the usable space. For the AI-100SS, filling requires opening the cover and removing the basket; its drain cap is on the side. A snug compartment can make either task awkward even when the closed machine fits.
Before choosing a permanent spot, check your model's lid travel, removable parts and drain location. Plan where rinse water will go without tipping the machine or spilling near an outlet. Keep the appliance assembled; do not remove a panel to create a different drainage route.
For hands-on AI-100SS cleaning or service, its manual requires turning the unit off and unplugging it. A separate powered cleaning program, where present, follows its own instructions. Our standalone ice-maker cleaning and rinsing guide explains that distinction.
GOHALL Ice Machine Cleaner Tablets address mineral deposits and everyday buildup in compatible standalone machines. They cannot provide missing airflow or correct an unsuitable location. The Opal and Newair placement examples do not establish GOHALL cleaner compatibility. Confirm cleaner and procedure permission in the appliance instructions; complete the required fresh-water rinses and discard cleaning ice before returning to production. Refrigerator and freezer ice makers are excluded.
If the machine will only sit in the cabinet between uses
Treat that as storage, rather than a running location. The draining and storage guide covers the model-specific water and drying work before putting a countertop machine away. Take it back to an approved operating location before use.
If fresh batches become smaller or slower after a move, compare the new spot with the installation rules before adding cleaner. Existing ice melting in the basket is a separate question: the basket-melting guide explains why a countertop bin may not keep ice frozen.
Questions about ice-maker placement
Is leaving the cabinet door open enough?
It does not establish that the required rear and side gaps exist. Check every clearance and the model's cabinet-installation permission. Opening a door cannot replace those measurements.
Can I use the same clearance for every countertop ice maker?
No. The GE support page and AI-100SS manual above give different requirements. Follow the document matching the machine you own, rather than a general countertop rule.