To get specific instructions and an example for your brand, click on one of the links below:
Affinity    Aire-Flo   Airquest   Allied Air  
Amana  American Standard    Ameristar    
Arcoaire  Bard   Bosch  Bryant   CAC/BDP
Carrier  Champion  Climatemaster  Coleman 
Coleman-Evcon Comfort Pack  Comfortmaker
Concord   Cumberland    Daikin   Day & Night
Ducane DuctlessAire EcoTemp FHP (Florida Heat Pump)
Franklin  Friedrich  Frigidaire  Fujitsu   GE 
Gibson   Goodman    Grandaire    Guardian
Heil International Comfort Inter-City Products
Janitrol   Kelvinator   Lennox  LG  Luxaire
Magic-Pak Maytag Midea Miller  Mitsubishi  
MrCool  Nordyne  National Comfort Products
Nortek  NuTone  Panasonic  Payne  Pioneer  
Rheem    Ruud  Samsung  Stylecrest Revolv
Sears Kenmore  Tempstar    Thermal Zone
Trane   Unitary Products    WeatherKing
Westinghouse  Xenon    York 

   It’s pretty simple for just about any system once you get the hang of it. Look for a number that is divisible by 6 or 12 somewhere in the center of the model number on the data plate at the side of the heat pump condenser (outdoor unit), like 12,18, 24, 30, 36, 42, 48, or 60. 

    A ton of air conditioning equals 12,000 BTU's so, for example a “24” in the middle of the model number indicates that it is a 2-ton system, a “30” means 2-1/2 tons, and the “42” in the middle of the model number at the top of the page means the system is 3-1/2 tons.

Here’s a few more examples:
Trane - 4TWR3030A1000AA - 2-1/2 tons
Carrier - 38BYC030360 - 3 tons
York - YCE48B21SA - 4 tons
Goodman  - CPRT36-1 - 3 tons
Trane -  TTR060C100A2 - 5 tons
Goodman -  GSH130241AC - 2 ton

    You probably noticed that the last model number had two numbers, “30” and “24,” that are both divisible by 6. Several of the others are the same way. Generally, the second number is the right one. Also, the number of tons of cooling capacity indicated is “nominal,” meaning that the actual BTU’s are approximately the number indicated, but may slightly more or less.

     If you are unsure whether you have found the right two numbers, you can double-check it by looking for the “RLA” rating on the data plate. RLA is an acronym for Rated Load Amperage, and is what the maximum amperage should be when the condenser is up and running. If you divide the RLA by 6 for older units and 5 or 6 for newer units, you should get a number that approximates (not exactly) the tonnage of the system. Make sure you use RLA and not LRA, Locked Rotor Amperage, which is the surge of amps necessary to overcome inertia and start the system. It averages around five times the RLA.

    To determine other key specs of your HVAC system, see one of these other blog posts: 

• How do I determine the age of my air conditioner?

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

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

 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 

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

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

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

• 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.