Where to find the model number on an air conditioner

A central air conditioner has two halves: the outside unit (the condenser, with the big fan) and an indoor coil on top of the furnace or in an air handler. Each has its own label. This guide is about the outside unit, whose rating plate is on the metal cabinet, usually near the service panel where the pipes and wires come in.

Where the label usually is

Most outdoor AC units: walk around the outside unit; the label is on the cabinet near the service panel, where the pipes go in.

By brand

• TraneThe label is on the top, right-rear of the outside unit.
• Carrier, BryantThe rating plate is on the back of the unit, above where the pipes connect.
• LennoxThe label (white, black letters) is near the service panel.
• Rheem, RuudThe model and serial tag is on the outside of the cabinet, near the top.

Each brand's spot is from that maker's own "where is my model number" page or manual, linked under Sources. Models vary, so if it isn't there, check the other spots above.

How to find and record the numbers

1. 1. Make it safeRead the label from outside the unit. Don't open the service panel (it has live power), and never open the house's electrical panel to look.
2. 2. Look in the usual spot firstWalk around the outside unit; the label is on the cabinet near the service panel, where the pipes go in.
3. 3. Find the two numbersLook for the words Model (or M/N, Mod.) and Serial (or S/N, Ser.). The model is the product; the serial is your one unit.
4. 4. Take a sharp photoUse the flashlight at an angle so the label doesn't glare, and get the whole label in the frame. A photo beats copying by hand: 0 and O, 1 and I, 5 and S are easy to mix up.
5. 5. Keep it where you'll find itSave the photo with the appliance's name, or write both numbers on the receipt or in your home records.

Model number or serial number?

The model number names the product: every unit of that model shares it, and it's what you need for the manual, replacement parts and recall searches. The serial number is your one unit. Makers use it for warranty claims, and many build the date it was made into it, which is how you can tell an appliance's age without the receipt. Each maker uses its own code for the date, so look up your brand's pattern or ask the maker before you trust a guess.

What you'll use it for

The rating plate shows the refrigerant the system uses. That matters for older systems: the U.S. ended new production and import of R-22 (HCFC-22) in 2020, according to EPA's phaseout schedule, so a system that uses it can only be recharged from existing supplies. Many brands also put the size in the model number as thousands of BTU per hour (for example 036 for 36,000, which is 3 tons), but codes vary, so confirm with the manual. And the serial number dates the unit, which helps when you're weighing a repair against a replacement.

If the label isn't there

Labels on outdoor units fade in the sun. Check all four sides, including the side facing the house, and the top corners. If it's unreadable, the indoor coil's label, the installer's invoice or a sticker from the last service visit may list the model.

Questions people ask