How to read a nameplate

Model, refrigerant, charge, MCA and max fuse — which line answers which question, on one labeled drawing.

Checked against the sources below on October 7, 2026

The short answer

Read the refrigerant line first. Then the model number — it is what identifies the unit, and it is what you type into the lookup. On the electrical lines, MCA and max fuse are two different numbers for two different jobs: one is about the wire, the other about the breaker.

The nameplate, line by line

A typical outdoor-unit nameplate. Layout and wording vary by manufacturer; the lines are the same.

Line	What it tells you
Model number	Identifies the product. On most brands the nominal capacity is coded in it, in thousands of BTU per hour.
Serial number	Identifies this one unit. The manufacture date is coded in it; the format is different for every brand.
Refrigerant	The refrigerant the unit was designed and charged for. R-32 and R-454B are not interchangeable with each other or with R-410A.
Factory charge	How much refrigerant the unit left the factory with.
Design pressure	The highest pressure each side of the system is built for. It is a limit, not a normal operating pressure.
Volts · phase · Hz	The electrical supply the unit needs.
RLA and LRA	Compressor rated-load amps (running) and locked-rotor amps (the surge at start-up).
FLA	Full-load amps of the fan motor.
MCA	Minimum circuit ampacity: the smallest ampacity the supply conductors may have.
Max fuse / breaker	The largest overcurrent device allowed on the circuit. It is never the same number as MCA.
Listing mark	The mark of the laboratory that tested the unit to the safety standard.

How conductors and overcurrent protection are sized from MCA and max fuse is set by the electrical code adopted where the equipment is installed.

Finding the size in the model number

One ton of cooling is 12,000 BTU per hour. Most manufacturers put the nominal capacity in the model number as a two- or three-digit code:

Code in the model	BTU/h (nominal)	Tons
018	18,000	1.5
024	24,000	2
030	30,000	2.5
036	36,000	3
042	42,000	3.5
048	48,000	4
060	60,000	5

Nominal is not certified

The code is the size the unit is sold as. The certified capacity is a different number, and it depends on the indoor unit: a unit sold as 2-ton can certify at 25,400 BTU/h with one indoor match and a different figure with another. The lookup shows the nominal size and the certified BTU/h side by side.

What is new on an A2L unit

A fire warning on the outside of the equipment: “WARNING—Risk of Fire. Flammable Refrigerant Used. To Be Repaired Only By Trained Service Personnel. Do Not Puncture Refrigerant Tubing.”
Red marking at the service ports and wherever the refrigerant circuit might be opened.
On the indoor unit, near the nameplate: the minimum installation height and the minimum room area. They exist because the amount of an A2L refrigerant a unit may hold is tied to the size of the room it serves.
The refrigerant and the date of manufacture. On a field-charged system that date is the date of first charge, filled in when the system is first charged.

The refrigerant quick reference →

From the nameplate to the lookup

Type the model number as you read it — outdoor or indoor unit. Partial numbers work, and dashes and spaces do not matter. The serial number is not searchable: it identifies one unit, and the certification belongs to the model. Try it →Try it →

Sources

40 CFR Part 82, Subpart G, Appendix W — the flammable-refrigerant warning and the minimum room area marking on A2L equipment
40 CFR 84.58 — Labeling — refrigerant and date of manufacture (or first charge) on new systems
16 CFR Part 305 — Energy Labeling Rule — the yellow EnergyGuide label, which is separate from the nameplate

Federal rules change. This page reports what the sources said on the date above; the source is the authority, and state or local rules can be stricter. It is reference material, not legal advice and not installation guidance.