Diagnose noise by location
A Commercial Cool refrigerator makes several noises by design: gurgling as refrigerant moves, ticking as controls switch, and a hum whenever the compressor runs. What is worth investigating is a new noise, a noise that changes when you open the door, and a noise accompanied by anything else — poor cooling, frost, or a warm cabinet. four model numbers share the CCUN designation. They are in the table below, and the trailing letters that separate them are finish and trim codes rather than different mechanisms — the fault below behaves the same across the list.
What you actually observe
- A whine that follows the compressor exactly — Starts and stops with it, which locates it at the back and rules out the interior.
- Scraping when the cabinet is nudged — Something in contact that moves when the unit does — a line against the shell, or a panel edge.
- A thud every few hours — The defrost cycle: ice shifting, water running, a control switching. Unwelcome and usually normal.
- Noise louder with the cabinet full than empty — Resonance through the contents, which means the sound is being transmitted rather than generated inside.
- NEAR MISS — noise plus water on the floor — Then the leak is the fault worth chasing, and the noise is very likely incidental.
Causes, most likely first on the CCUN line
- Something touching something — First: a line against the shell, a panel against a wall, a cabinet against a cupboard. The test is to press gently at various points while it runs and listen for the noise to stop.
- A blade against ice — Second: the classic tick or chirp, and the reason a noise complaint on a frost-free cabinet often turns into a defrost diagnosis.
- Sounds that are supposed to happen — Third: refrigerant gurgle, defrost water, liner clicks. Worth naming so they can be set aside with confidence.
- Mechanical failure in the sealed system — Last and least likely, but the one to act on where a hum has deepened while cooling has got worse.
Check in this order, and why that order
- Note whether it is constant or cyclic — A noise that follows the compressor cycle is mechanical; a noise that appears once every several hours is usually the defrost system.
- Press-test the panels while it runs — Gentle pressure at the sides and back. A rattle that stops under your hand is resonance and needs packing or levelling, not parts.
- Pull the unit out and listen again — Noise that halves when the cabinet is away from the wall was never a fault in the first place.
- Escalate anything metallic or new — A fan bearing, a compressor mount or a relay. All are behind panels on a live cabinet, so that is where owner work ends.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. A fan that ticks against ice should not be freed with a screwdriver or a heat gun: unplug the cabinet, empty it and let the ice thaw naturally. Never run a refrigerator with a rear panel removed to listen to it, and never wedge a door switch to keep a fan running while you investigate.
Models this page covers
Reference| Model number | Family key |
|---|---|
| CCUN28B | commercial-cool:refrigerator:ccun |
| CCUN28BV | commercial-cool:refrigerator:ccun |
| CCUN28W | commercial-cool:refrigerator:ccun |
| CCUN28WV | commercial-cool:refrigerator:ccun |
Where the owner line is on these models
Stop and call if the unit clicks every few minutes without cooling, if the sound is a grind rather than a rattle, or if a fan is audibly catching. Otherwise work through levelling, clearance, the drip tray and an empty-cabinet test, and be honest about the sounds that are normal on a small sealed system: gurgling, trickling, popping and a hum that is simply audible in a quiet room. Whichever of the four models in the table above you have, quote the full number from the rating plate when you call — the family letters alone will not get the right part.
Other CCUN problems we cover
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
