Photograph of an air conditioning system data tag or sticker showing the manufacturer's specifications Air Conditioning & Heat Pump Data Tags
BTUs, Tons, Equipment Age

  • DATA TAGS on AIR CONDITIONERS - CONTENTS: How to read, decode, & translate A/C & heat pump data tags & stickers - Air conditioner BTUs, Tons, Age: decoded on data tags. Air conditioner electrical requirements & refrigerant needs. Air conditioner cooling capacity coded in model numbers. Air conditioner and heat pump manufacturer's information; serial number gives A/C age
  • POST a QUESTION or READ FAQs about how to determine the age of an air conditioner or heat pump

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HVAC data tag decoding: This article explains and translates all of the data found on information tags and stickers used on air conditioning and heat pump equipment. This article series answers most questions about air conditioning systems.

This article provides help in decoding air conditioner, boiler, furnace, heat pump, water heater data tags and determining the age, model, or specifications of that equipment.

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A/C DATA TAGS - Air conditioner & heat pump data tags de-coded

Photograph of the information sticker from a residential air conditioning compressor unitHere we explain the meaning of each of the data names and contents of typical air conditioner system data tags. We include examples of how to make use of the data to estimate equipment age, capacity, and even its condition. (Not all of the terms we define below will appear on all equipment or motor tags.)

The photo at page top shows the main data sticker from a 1997 split system air conditioning compressor/condenser unit.

[Click to enlarge any image]

This model, made by Sanyo, Inc., provides easy-to-read basic data about the system including its year of manufacture, refrigerant, electrical requirements, and service information.

Article Contents

The photo shown here is for a conventional (non-split) residential air conditioning compressor unit.

Unless it has been painted-over or lost, on most air conditioners and heat pumps, a metal, foil, or plastic tag or data sticker is usually affixed to the outdoor air conditioner or heat pump compressor/condenser housing.

Depending on the age and equipment manufacturer the format and content of data on this tag varies, but typically the tag will allow you to discover some or all of the considerable amount of data listed here:

How to estimate air conditioner size (C) Carson Dunlop Associates

  • Manufacturer: The air conditioning equipment manufacturer.

    Sketch at left on guessing the size of an air conditioner system is compliments of Carson Dunlop Associates. As we cite at REFERENCES, Carson Dunlop also provide a Technical Reference Guide with extensive details that aid in decoding HVAC equipment serial numbers and data tags.
  • Model Number, Serial Number, and Cooling Capacity: sometimes cooling capacity is coded into the model number but on most newer units including the Sanyo compressor shown here, cooling capacity is stated explicitly. On older equipment the BTUH cooling capacity may be encoded in the model numbers.

    RATED COOLING CAPACITY discusses how to read the cooling capacity in BTUH or tons from air conditioning or heat pump tags. The serial number of modern HVAC equipment encodes the year and month of manufacture - thus the age of the equipment is shown. For equipment where the month and year of manufacture is not stated in plain English, Carson Dunlop provides a Technical Reference Guide manual that decodes that data.
  • Voltage or VAC for the compressor and separately for the blower fan. In addition to specifying voltage, the cycles (50HZ or 60HZ) and current phases (typically one phase for residential equipment) may be specified.

  • Branch Circuit Selection Current- BCSC: recommended for determining the required size of the branch circuit conductors (wiring) supplying the equipment.

  • Locked Rotor Amperage - LRA specifies the maximum current that the motor will draw when the motor's rotor is unable to move [locked] (or under any other condition). [NEC Table 430-152-A]. LRA on an air conditioning compressor describes the amperage drawn by the motor briefly during motor startup. Locked rotor amperage is also called inrush current. Because it takes a lot of energy (torque) to get the still parts of an electric motor turning, LRA will always be higher than the current used to keep the motor turning once it has started (FLA or RLA). This is particularly true if the motor has an additional load (resistance to turning) at startup, such as trying to start an air conditioning compressor against refrigerant head pressure inside the compressor unit.

    The LRA of electric motors is 700% - 850% of rated current of the motor (or in some sources 5 to 7 times greater than RLA or FLA - a lot. The motor's circuit breaker, especially on an air conditioning system which can draw high initial amps (LRA) will be sized to protect the electrical wiring of the motor circuit, but the breaker also will be chosen to tolerate a brief, high initial current draw to avoid nuisance tripping. In other words, the inrush current, because it is brief, does not need to figure in the selection of the wire sizing when wiring or fusing the motor, except to avoid nuisance tripping.

    The relationship between the LRA and full load amperage (FLA) varies depending on the design of the electric motor being rated. Motors built to NEMA standards are assigned codes A through H. Each letter can be translated into multiplier x FLA to give LRA.

    To assist in avoiding nuisance tripping during compressor startup when high current is drawn momentarily, A/C compressor circuit breakers may be permitted to be one size larger than the circuit breaker required by the wire size itself.

    LRA also affects the choice of the electric motor starter. Finally, an air conditioner motor will also draw its LRA current if the motor is frozen or stuck or has bad bearings - which we hope will quickly trip the circuit breaker or blow the circuit fuse. -- Thanks to Patrick Greaux for requesting clarification of LRA.

  • Minimum Circuit Ampacity - MCA: MCA can be used to determine the required size of branch circuit conductors (wiring and also control switches) supplying the equipment. [For example, using NEC Table 310-16 in the 60 degree column as required in 110-14]. However some experts recommend using BCSC. [Using the "minimum permitted" sized wire rather than the optimum-size to a compressor may save a few dollars at installation but may increase system operating costs and it may be less safe than using a larger conductor.]

  • Maximum Fuse or HACR type Breaker: specifies the maximum overcurrent protection or MOP to be used to protect the equipment. The permitted ampacity of the equipment electrical circuit protection (fuse or circuit breaker amps) expressed as MOP or Maximum Overcurrent Protection. If MOP is specified, the breaker or fuse protecting the equipment should match this number.

    A hermetic compressor draws varying amounts of current as its internal pressure changes during operation. Current draw is higher when starting the motor, and highest if the motor is starting against its highest back pressure such as when a unit is turned off and then back on in the middle of operation. Because fusing an air conditioning compressor at the minimum level can result in blown fuses or tripped breakers during these intervals of heavy current draw during compressor startup, compressors are either protected by a slow-blow fuse or a somewhat larger than minimum circuit breaker.]

    On some older equipment MOP is not specified. Only in the case that MOP is not specified can the overcurrent protection required be determined by the alternative means: [RLA OR BCSC whichever is greater x 175%], or if the compressor keeps tripping that device or blowing that fuse, RLA x 225% might be used. The National Electrical Code (NEC) specifies the degree to which a breaker or fuse may exceed the RLA.

  • Rated Load Amperage or Running Load Amperage - RLA, also called Rated Load Current or RLC on some equipment. This is the manufacturer's anticipated load during normal usage, that is, the current drawn when the motor is running normally. RLA is usually similar to FLA in amount.

    Typically RLA is about about 64% of the maximum load current. See NEC section 440-2.

    We sometimes can guess the size (tons of cooling capacity) of an air conditioning compressor by dividing the RLA number by 6, 7, or 8. For example a compressor RLA of 21 amps may be about 3 tons of cooling capacity (21/7). For more accurate means of determining air conditioner cooling capacity by several means including decoding the data tag, see COOLING CAPACITY, RATED. In air conditioning systems, typically a motor provides about one horsepower (HP) per ton of cooling capacity.

  • Full Load Amperage - FLA full load motor current draw, level at which the motor can be operated without damage. FLA is similar to RLA in amount. The FLA amperage is the current the motor will draw when the motor is
    loaded up to its rated horsepower. If an electric motor is running at less than its rated horsepower it will draw less than its FLA current.

    If an electric motor is trying to run at more than its rated horsepower, it will draw more than its FLA current. A technician can measure the actual motor amperage (current draw) and compare it to the FLA to quickly tell if a motor is overloaded - in the case of air conditioning a running current draw above FLA may mean that the compressor is near its end of life.

  • Maximum Continuous Current - MCC not usually supplied, this is the most current that the compressor can draw without being damaged. [Typically about 150% of RLA.]

  • BTUH Cooling Capacity: The A/C system cooling capacity, either explicitly stated in thousands of BTU's (British Thermal Units) per hour (BTUH) or implicitly given by other data, or coded in the unit's model number.

  • The month and year of manufacture, possibly also encoded in the unit serial number. Since the typical life of an A/C compressor is about ten years, one would like to know the probable age of the equipment.
Energy Guide Sticker for Carrier High Efficiency Gas Furnace (C) Daniel Friedman
  • The Energy Efficiency Ratio of cooling equipment is basically the amount of electricity you consume to obtain a given amount of cooling ability. It's expressed as (KW per hour of electricity used) / Thousand BTUs - this number is probably not going to be found on the equipment itself but may be in its documentation.

    You will usually find this data in the bright yellow EnergyGuide sticker that is more often on a side of the equipment rather than encoded in the equipment's own data tag.


    Photo courtesy Eric Galow, Galow Homes, Poughkeepsie, New York.

  • Refrigerant type is shown somewhere on every air conditioner, heat pump, or other cooling compressors. The tag shown here notes that the system uses [the now obsolete] R22 refrigerant.
  • Voltage - the voltage at which the motor is intended to be operated. Motors can normally operate fine at voltages within 10% of the rated voltage level on the data plate.
  • Month and year of manufacture is shown either explicitly as on the Sanyo compressor data tag shown here or this data may be encoded in the unit's serial number. Carson Dunlop provides a manual that decodes more of that data so that you can know the age of the compressor or air handler. That is, the date of its manufacture, not the date of its installation. The installation date of air conditioning equipment may be recorded on a service company's data tag, on receipts, or even inked inside of the steel cabinet of the equipment.

Photograph of a modified air conditioning system information data tag - hiding info Modified, damaged, or torn air conditioning equipment information data tags can make age, capacity, and repair of any equipment more difficult. For the air conditioning compressor unit shown here, all we know is that the manufacturer was Singer. Model numbers and serial number appear to have been cut away from the data tag. Why?

Sometimes when equipment data labels are removed or obscured a building buyer or a home inspector may raise a concern that the unit installed was different than that which the was ordered or that it is of questionable origin. On rare occasion that might be the case..

But Ratib Baker, a member of member of Refrigeration Service Engineers Society (RSES), informs us that during the 1980's HVAC equipment manufacturers used a type of label which lacked UV resistance, faded, cracked, and eventually peeled away from the equipment, making equipment identification and ordering of replacement parts difficult.

Mr. Baker wrote (October 2008) that in the 1980's "the [HVAC compressor] label's protective mylar surface was damaged by the printing of the model and serial numbers and the electrical data which allowed the UV from the sun to destroy those areas. Upon discovering that they did not stand up to weather, most manufacturers started putting a second label inside the electrical compartment. Eventually better labels were designed, but some of the better manufacturers still put a second label in the unit."

Where a data tag or label on equipment is damaged or missing, check further for more label data including inside the unit's enclosure. Service technicians may have written the model and serial number data in indelible marker, or the manufacturer may have provided a second data label inside the unit - check HVAC equipment with lost or damaged labels to see if you can find that data elsewhere. You may also find equipment identification details in the installation and service manuals for the equipment if those have been kept in the building. Look around the indoor equipment for those documents.

What we can say from the label in the photograph above is that by 2007 when the photo was taken by an ASHI inspector, this particular equipment was at least 23 years old - older than its usual anticipated life expectancy: the Singer brand on air conditioners was dropped in 1984.

Where to Buy Carson Dunlop Associates' Technical Reference Guide decodes equipment data tags for air conditioners, heat pumps, etc.

Carson Dunlop Associates' Technical Reference Guide (below) provides the most extensive HVAC equipment data tag decoder & other information to determine the age of boilers, furnaces, water heaters, air conditioners, and heat pumps by decoding the product serial number.

HVAC Technical Reference Guide (C) Carson Dunlop Associates

For the most complete and very detailed HVAC equipment data tag and age decoding information anywhere (about 128 manufacturers & brands), Alan Carson and Bob Dunlop, of Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates'

Technical Reference Guide
to manufacturer's model and serial number information for heating and cooling equipment

Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.

Here at we discuss different types of heating systems (octopus furnaces, forced air heating systems, steam boilers, forced hot water boilers, high efficiency systems) and fuel types (coal, oil, gas) as an aid in determining the age of a home or other building. Heat pumps are discussed at AIR CONDITIONING & HEAT PUMP SYSTEMS

The Carson Dunlop Technical Reference Guide provides both equipment data tag decoding data and also manufacturer contact information as well as historical dates for many brands of heating and cooling equipment. Included in the manufacturers listed are also makers of ancillary equipment such as controls, circulator pumps, etc., not just boilers, furnaces, and heat pumps themselves.

References for HVAC controls & switches

Example HVACR Air Conditioning & Heat Pump Equipment Data Tags & Decoding Tips

Whirlpool Corporation Equipment Data Tag Translator

Whirlpool air conditionre or heat pump data tag translator table

Source: Whirlpool WGPH45 Packaged Heat Pump, Product Specifications [17]

[Click to enlarge any image]

Watch out for Confusing or MisReading Letters & Numerals on Old HVAC Equipment Data Tabs

Especially when equipment is old or has been located outside where its data tag can become obscured, faded, or damaged, it is easy to confuse as certain numeric digits some alphabetic characters, and vice versa.

Our table below gives some confusion examples to watch for. So if information about model numbers or serial numbers for a given manufacturer specifies that that company use a mix of alphabetic and numeric characters (E.G. General Electric), and you see only numeric, look again to see if you're making a mistake.

Table of HVAC Data Tag De-Coding Errors

Numeric Character Confused
With alphabetic or numeric
Numeric 0 - zero Alphabetic O
1 I
1 L
2 S
2 Z
3 E (reading upside down)
3 8
5 S
6 9 (reading upside down)
6 G
7 2
8 B
9 6 (reading upside down)

Other information tags and stickers on air conditioners and heat pumps

Service and refrigerant connections

Photograph of a split system air conditioner (C) Daniel Friedman

Service information and/or refrigerant piping hook-up may be provided by a separate sticker on the air conditioner compressor/condenser unit, such as the piping arrangements shown on this split-unit compressor side.

More critical service data such as refrigerant type and operating pressures are recorded in the main data tag shown earlier.

Air conditioner or heat pump basic wiring diagrams

Photograph of an air conditioner wiring diagram. (C) Daniel Friedman

A basic hook-up wiring diagram may be provided by the manufacturer on a separate sticker on the air conditioner compressor/condenser unit such as this one from the Sanyo unit.

Air conditioner or heat pump safety warnings

Photograph of the safety stickers on a residential air conditioning system

Safety warnings for consumers and service people also appear on tags or stickers on modern air conditioning and heat pump units, such as shown in the photo above.

Data information tags on commercial air conditioning and heat pumps

Photograph of a commercial air conditioning rooftop unit sticker indicating cooling or heating capacity as a function of air temperature (C) Daniel Friedman Photograph of a refrigerant charging chart for a commercial air conditioning rooftop mounted unit (C) Daniel Friedman

Commercial air conditioning or A/C/Heat pump units such as the rooftop unit from which these data tag photos were taken often provides additional and critical capacity and service data.

[Click to enlarge any image]

The first or left hand tag shows the equipment's operating capacity in both BTUH and watts, and shows a maximum air temperature at the unit. The second photo at right shows a refrigerant charging chart that must be consulted by the service technician who monitors suction line (low pressure or return line) temperature and pressure.

Examples of HVAC Data Tag Decoding & Identification Questions

Reader Question: age of a GE air condenser unit

Could you help us determine the age of a General Electric central air condenser.
Model TA36H1F01 S/N 205100925
This unit appears to be extremely old, but would appreciate any help you can give me. - John 6/1/12


John, Carson Dunlop's Technical Reference Guide has several pages of GE equipment data decoding information, including the observation that

beginning in 1944 GE coded the age in the last three digits of the serial number, with the year in the third from last position.

But the GE serial number codes on air conditioners & heat pumps used letters (N-Z = months Jan-Dec) and Year A-Y = 1944-1964, then repeated). Your serial number does not conform to the known codes for General Electric air conditioners. GE used letters not digits for month and year as I explained above.

Is it possible you are mis-reading a letter "Z" as a numeric "2" or a P or R as a "9" and an "S" as a "5" ?

Examples of troubles reading old fuzzy or partly obscured serial numbers or model numbers on HVAC equipment are in our article just above. So if your 2 and 5 are really SS the unit could be as old as May 1959 or perhaps more likely, as recent as 1980.

Send us a sharp focused photo of the entire label if you can and I'll comment further.

The Model Number you provided indicates in the two digits following the TA (TA36) 36,000 BTU/h

GE no longer makes A/C units - heat pumps were sold to Trane, Canada.

Reader Question: age & data tag decoding for Command Aire equipment

I am looking to replace a 30+ year old cooling/heating wall convector from a New York high-rise apartment unit.

Attached is the current unit in operation, and there a total of four (4) located in separate spaces within the unit.

[Click to enlarge any image]

Command Aire wall convector unit identification (C) InspectApedia DC Command Aire wall convector unit identification (C) InspectApedia DC

Can you please tell me if you know what kind of a unit this is from the poor quality photo (Command-Air(?)), and if there are modern replacements I can look into that possibly can be controlled from a wall plate control next to a light switch (for example). - D.C. 8/21/2014


I'm not what I'm looking at in your photo.

But some basic information about wall convector units used for heating and/or cooling is at


Typically in a high rise apartment the energy source for heating and cooling will be piped from a common building source. You'll want to know what your building supplies before thinking about replacing the equipment.

Reader Follow-up:

The photo was a poor shot of the model label sent by the contractor currently remodeling the apartment. The units are enclosed within a built-in wooden lacquer cabinet, similar to the attached photos show. I was trying to make out the unit name, and I believe it is an early 80’s Command-Aire model, about 62” wide by 12” deep. I’ve also attached a stand-alone model, with the controls on top beneath the grill.

I’m not sure about the building supply details yet, since I have not received information from the contractor, but I’m just trying to find a comparably model to replace this unit(s). I believe the overall size and top diffuser gives me a head start to look into a Trane Type AK model, just to start comparing.


Command Aire brand was later bought by Trane - so when you know what type and model you've got installed that'd be a place to start looking for a compatible replacement.

When you have a clear image of the unit's data tag you'll see brand, model, serial number that will decode into just what is installed. There's little point in looking for equipment and prices before you know what kind of equipment works with your buiding's infrastructure.

Command Aire Data Tag BTUh Capacity Decoding

For example, Command Aire included heat pumps (which you may not have)
SWPR 261 thru 611 water source heatpumps.
The three digit number following SWPR 261 indiates the unit BTUs
261 = 24000 BTUh
281 = 30000 BTUh
361= 36000 BTUh
411 = 42000 BTUh
511= 49000 BTUh
611= 62000 BTUh

Contact Trane (commercial / residential) at

(800) 945-5884

American Standard Heating & Air Conditioning
Customer Relations
20 Corporate Woods Dr.,
Bridgeton, MO 63044



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