Heating & AC Repair

How to Identify Your System Make, Model, Size, Age and Type

There are many different system types, we’ll focus on the systems that make up 90% of what is commonly installed today and how to identify what you have.

Step 1: Visual Identification of System Type

Package Units

A package unit is an “all-in-one” system that does everything in one large box. You can best identify the package unit by looking at the unit (outdoors). If you have a package unit you will notice a large hood made of metal that looks like a box between the unit and your house. This is called the rain shield and it protects the ductwork from rain, debris, and critters. Because a package unit is all-in-one box the supply and return ducts connect right to the unit and the heated or conditioned air is delivered right into the house.

The actual look will vary based on equipment but when you can see the metal box between the unit and the house like the picture below you’ve got a package unit. 

Split System

The split A/C and Furnace is the type of system most people are familiar with. In this setup the outdoor unit has the shape that most people associate the air-conditioners. This is the condensing unit. Inside, usually in the attic, crawlspace, or closet is the component that contains the blower, furnace (if equipped) and evaporator coil.  The condensing unit will be located outside the house and has a more traditional look, similar to the picture below.


Step 2: Identifying the Make, Model, Age, and Size

To identify the make, model, age, and size you will need to find the manufacturers label. Do this on the outdoor unit, whether it’s a split system or package system. On a package system it is usually on the right side of the equipment, near where the gas and power connect to the system. On a split system the label is often found on the same side as the refrigerant lines enter the system. On some older systems near the bottom right above the lines on newer systems closer to the top. 

On this label you’ll find lots of numbers and letters. The ones we are most interested in are the model and serial numbers. From these we can determine the age, size, and type of equipment.

Make and Model:

The make should be pretty easy to figure out. Normally they have a logo prominently placed. If not, it can be found on the label pretty easily. The model is designated as a field on the label and is easy to identify. Each manufacturer categorizes their equipment differently. Some like Trane encode the efficiency of the equipment in the model, others do not. You can look up the model of your equipment, its features and efficiency using the model and make on the label and Google.


Basically all manufacturers encode the size or tonnage of their systems into the model number. Tonnage is a measure of BTU’s in 12,000 BTU increments. For example a 1 ton system would have 12,000 BTU’s. A 2.5 ton system would have 30,000 BTU’s. These are reflected in the model numbers near the middle and often followed by a letter. 

Below are a couple examples to look at:

38EZA048310 is a Carrier 48,000 BTU or 4 ton system

4TTZ0048A1000AA is a Trane 48,000 BTU or 4 ton system 

If you are unable to read the label you can look down into the condensing unit from the top to see the compressor and often use the compressor part number to determine the tonnage using Google. 


The age is generally encoded into the serial number. Many manufacturers do it differently and most have changed the way they do it over the years. Below are the most popular brands and how they encode the year within the last 20 years or so. For older equipment Google can be pretty helpful. 

Carrier/Payne/BryantCarrier systems made in the last 20 years or so encode the week and year of manufacture within the first 4 digits. The first 2 are the week of the year (1-52) and the second are the year. For example 0199 would mean the system was made the first week of January in 1999. 


Trane/American StandardMany Trane products have the date they were manufactured right on the label in the top right corner. Start there, if there isn’t a manufacturing date present then look at the serial number. There are 2 styles that were used within the last 20 years. 

  • Style 1 starts with a letter which represents the manufacturing location and then 2 numbers which is the last 2 digits of the year manufactured (in 2000). For example C12A00152 means Clarksville Plant. 
  • Style 2 starts with numbers and the first 2 numbers are the year. For example 1125KREAA was manufactured in 2011. This style also has the year of manufacture commonly listed on the label so you won’t need to decode the serial number.
LennoxModern Lennox system serial numbers contain 4 numbers followed by a letter. The first 2 numbers represent the factory where they were manufactured, the second 2 numbers are the year and the letter is the month where A is January, B is February, etc. An example would be 5800A12345. 58 is the factory, 00 represents the year 2000 and A means it was manufactured in January.
GoodmanGoodman serial numbers are 10 digit numerical where the month and year are encoded in the first 4 digits. The year is the first 2 and the month the second 2. For example 1404123456 is manufactured is April 2014. 
Rheem/RuudModern Rheem systems use two styles of date encoded in the serial number. 

  • Style 1 starts with a letter followed by the week and year of manufacture. W011012345 would be manufactured in January of 2010.
  • Style 2 follows the letter in the middle of the serial number with the week and year of manufacture. For example CB5D302F0998 would be manufactured in March of 1998.