Diagnose noise by location
A new noise is worth investigating and an old one usually is not. On a Comptree Inc cabinet the sounds that deserve attention are a fan clipping frost inside, a relay clicking without a start, and a hum that has deepened as the cabinet warmed. Everything else — gurgle, trickle, tick, pop — is the system doing what it does. The MXBC designation spans five model numbers in the table below. Which one you have decides the part number, not the repair — the fault below is the same across the line.
What you actually observe
- Humming that rises and falls through the day — A compressor loading and unloading against a warm room, not a fault by itself.
- A rattle that appeared after a big shop — Bottles and containers touching, or a shelf no longer seated. Empty it and run it to check.
- Buzzing through the floor rather than through the air — Structural transmission. A suspended floor amplifies a perfectly healthy compressor.
- Fan noise that continues with the door open — The door switch should stop the internal fan. If it does not, the switch has failed.
- NEAR MISS — a click a few seconds after the door closes — That is the fan restarting and a control switching. Normal on every cabinet of this type.
Most likely first
- The evaporator fan — Ranked first when the noise comes from inside the cabinet and changes as the door opens. The door switch stops that fan, so the door test identifies it without any tools.
- Installation and levelling — Second. Feet that were never wound out, a floor that slopes, or a cabinet pushed against a wall. Free to fix and instantly obvious once found.
- Loose parts in the compressor compartment — Third. Drip trays, cable clips and the occasional dropped object. Visible with a torch, with the unit unplugged and pulled out.
- Compressor, mounts and relay — Last. These are behind a panel on a live appliance, and the relay in particular should be diagnosed rather than swapped on a guess.
Check in this order, and why that order
- Ask what else changed — A noise that arrived with poor cooling, frost or a warm cabinet is a symptom of that fault and should be diagnosed as that fault.
- Empty the cabinet and run it briefly — Bottles touching, shelves half-seated and loose accessories imitate mechanical noise convincingly.
- Test the door switch — Press it by hand and listen. Fan noise that continues with the door open means the switch has failed and the fan is running when it should not.
- Then call, with the location — Where the sound is and when it happens decides what the technician brings. It is the most useful sentence you can give them.
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. Levelling the cabinet, checking clearance, reseating a drip tray and listening at the door need no panel off at all. Do not put your hand into a compressor compartment or near a fan blade on a running unit, and treat moving a full cabinet as a two-person job rather than a shove.
Models this page covers
Reference| Model number | Family key |
|---|---|
| MXBC-90 | comptree-inc:refrigerator:mxbc |
| MXBC-90-A | comptree-inc:refrigerator:mxbc |
| MXBC-90-B | comptree-inc:refrigerator:mxbc |
| MXBC-90-C | comptree-inc:refrigerator:mxbc |
| MXBC-90-D | comptree-inc:refrigerator:mxbc |
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. The five models listed share this diagnosis but not their part numbers, so have the rating plate to hand before the visit is booked.
Other MXBC 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.
