The second letter of the serial number of a GE Zoneline PTAC air conditioner or heat pump indicates the year of manufacture, based on a 12-year repeating cycle:
A = 2013, 2001, 1989
D = 2014, 2002, 1990
F = 2015, 2003, 1991
G = 2016, 2004, 1992
H = 2017, 2005, 1993
L = 2018, 2006, 1994
M = 2019, 2007, 1995
R = 2020, 2008, 1996
S = 2021, 2009, 1997
T = 2022, 2010, 1998
V = 2023, 2011, 1999
Z = 2024, 2012, 2000 

    So the serial number ARN052A100AC indicates manufacture in 2020, 2008, or 1996. Older models may have fewer digits than this example. To determine which is the correct year, look into the fine print on the data sticker for a compliance standard, such as ASHRAE, which will include the year of the standard. Because manufacturing standards are updated every 3 to 6 years, it will only be near the correct date choice. The condition of the unit provides another hint.

    Then again, you might not need to decode the serial number, because the month and year of manufacture may be listed under “MFR DATE/DATE DE FABRICATION” on the data sticker.

    Also, see our article What is a PTAC unit?   

  To learn more about heating and air conditioning systems, see these other blog posts:

• How can I find out the SEER of my air conditioner? 

• My air conditioner won't turn on. What's wrong? 

• How can I find out the size of my air conditioner? 

• How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump? 

• Where is the air filter for my central air conditioner and furnace? I can’t find it? 

• Does an old air conditioner use more electricity as it ages? 

• How did homes stay cool in Florida before air conditioning? 

• What is wrong with an air conditioner when the air flow out of the vents is low?

• Why has the thermostat screen gone blank? 

• Why does it take so long to cool a house when an air conditioner has been off for a while? 

• Why is my air conditioner not cooling enough? 

• What are the most common problems with wall/window air conditioners?  

• Will closing doors reduce my heating and cooling costs? 

   Visit our HEATING AND AIR CONDITIONING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.