Modern Carrier equipment (that would be all gas furnaces, air conditioners, and heat pumps) use a four-digit number as the first four places of the serial number for the age of the equipment. In the example below, this unit is a 2017 model.
It’s also important to note that modern Carrier equipment will also have a box printed on the data plate label with the month and year it was manufactured. The example below has it listed as JUN 2017
HOW CAN I AGE MY CARRIER HVAC EQUIPMENT USING THE SERIAL NUMBER?
Older Carrier equipment used a different format with their serial numbers. This style was utilized from the early 1960s through the late 1980s. Very few pieces of this old stuff are still in use today, but if you happen to have one still running- good for you! The layout on the old serial number was a single letter and then a single number. The number digit ran in a 10-year cycle, so it can be hard to figure out exactly the manufacture year.
This unit could be 1966, 1976, 1986. Most of the time you can look at it and tell roughly how old it is. If you still can’t tell how old it is, look for the ANSI (American National Standards Institute) number which should be printed on the label (along with the year). This is the standard in which the unit was produced, and is typically just a few years younger than the manufacture date.