The single best way to order the correct replacement part is to use numbers, not guesses. Photos and descriptions help, but the model number of your equipment and the part number on the failed component remove the guesswork. This guide shows you exactly where to find them and how to use them.
Find the Equipment Model Number
Every furnace, AC, and appliance has a rating plate with its model and serial number. Look here:
- Furnaces: on a label inside the blower compartment door, or on the inner cabinet wall.
- AC condensers: on a metal plate on the side of the outdoor unit.
- Appliances: around the door frame, behind a drawer, or on the back panel.
Write down the full model number exactly — every letter and digit matters. The serial number can also help identify the production run and the correct revision of a part.
Find the Part Number on the Failed Component
The fastest path to an exact match is the number printed on the old part itself. Most components carry one:
- Blower motors and condenser fan motors have a spec sticker listing HP, voltage, RPM, and a part number.
- Capacitors print microfarad and voltage right on the can.
- Control boards have a part number etched or labeled on the board.
- Igniters, gas valves, and switches are usually stamped or labeled with a manufacturer part number.
Decode the Specs That Must Match
Even with a part number, double-check the electrical and physical specs so you're confident in the fit:
- Motors: horsepower, voltage, RPM/speed taps, rotation direction, frame, and shaft size.
- Capacitors: exact microfarad value and equal-or-higher voltage rating.
- Gas valves: inlet/outlet size, gas type, pressure rating, and voltage.
- Boards and switches: connector layout, voltage, and the model the part was designed for.
Cross-Referencing Superseded Parts
Manufacturers frequently supersede older part numbers with updated versions. Your original number may now ship as a newer revision that fits and functions identically — often with improvements. If your number returns "no longer available," it almost always has a current replacement. That's exactly the kind of lookup our team handles every day.
Order With Confidence
Once you have the model and part numbers, matching a genuine OEM replacement is straightforward. And because genuine OEM parts fit exactly the first time, you avoid the return-and-reorder cycle that "universal" parts often cause — one more reason OEM is worth it for anything safety-critical.
Send us your model and part numbers and we'll confirm the exact fit before you buy — call 617-286-6694 or email support@proreplacementparts.com. Genuine OEM, US warehouses, 1–2 day handling.
What If You Can't Find the Numbers?
Sometimes the rating plate is faded, painted over, or hidden, and the old part's label is burnt beyond reading. You still have options. The original equipment's owner's manual or installation manual lists the model number and often a parts breakdown. A clear photo of the old part, its connector, and its mounting can help us identify it by appearance and measurements. And if you know the brand and the approximate age of the unit, we can frequently narrow it down. Don't guess and order the closest-looking part — reach out and let us help confirm it.
Measure Twice, Order Once
For mechanical parts, a tape measure and calipers prevent costly mistakes. Note shaft diameter and length on motors, the bolt-hole pattern on inducer and motor mounts, pipe sizes on gas valves, and overall dimensions on anything that has to fit a specific cavity. Pairing those measurements with the part number gives you the highest possible confidence that the replacement will drop in cleanly.
Frequently Asked Questions
Where is the model number on a furnace?
It's on the rating plate, usually inside the blower compartment door or on the inner cabinet wall. Record the entire model and serial number exactly, since a single character can point to a different part revision.
What if my part number is discontinued?
Discontinued numbers almost always have a current superseding replacement that fits and functions the same — often improved. Send us the original number and we'll cross-reference it to the part that ships today.
Can you find a part from just the model number?
Yes. With your equipment's model number we can identify the correct component and confirm the exact OEM replacement, even if you can't read the old part's label.
