Model number, serial number, part number: which one do you need?
What is the difference between a model number and a part number?
Four different numbers do four different jobs. The model number identifies the appliance and selects which parts list applies. The serial number identifies your individual unit and matters when the manufacturer split a part partway through production. The part number identifies one component and is what you order. The item number is just a row pointer inside one document. Only the part number is orderable.
What each one decides
People use these words interchangeably and then order the wrong thing. They are not interchangeable, and each one closes off a different kind of mistake.
- Model number — on the appliance label. Selects the parts list. Without it you are guessing which document applies.
- Serial number — on the same label. Selects between versions of a part when the maker changed it mid-production.
- Part number — in the parts list. The thing you actually order.
- Item number — beside the drawing. A row pointer, meaningful only inside that one document.
When the serial number is the deciding factor
Most of the time the serial is trivia. Sometimes it is the whole answer. Manufacturers split a part number partway through a production run and record the split directly in the parts list, with the serial as the cut-off.
When a list does that, the model alone cannot tell you which one to order. Two units of the same model, built either side of one serial number, take different components.
A real serial split, Norcold 2117 Series
- 628045 Shelf assy, glass/full (SERIAL# 11973837 & BELOW)
- 632030 Shelf assy, glass/full (SERIAL# 11973838 & ABOVE)
- Same shelf. Same model. One serial number apart.
Why the item number is not a part number
The item number is the small figure pointing at the drawing. It means "row 9 of this table" and nothing else. It is not unique across documents, it is not orderable, and it is the number most often mistaken for a part number by someone reading a diagram for the first time.
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Last checked 2026-08-30.