By Marcus Lindqvist · Updated September 10, 2026 · 5 min read
Short answer
A compressor nameplate lists the manufacturer, model, serial number, electrical ratings (voltage, phase, frequency, RLA, LRA), refrigerant, oil type, design pressures and approvals. Model numbers follow each manufacturer's own coding, so decode them with the maker's guide. The nameplate is the first thing to record before ordering parts, checking electrical protection or planning a refrigerant change.
The nameplate is a metal or printed label on the compressor that states what it is and the limits it was built for. Reading it correctly is the first step in ordering parts, checking electrical protection, confirming the refrigerant or planning a replacement. Photograph it before you do anything else, because plates fade and fall off.
What information is on a compressor nameplate?
Most nameplates show these fields:
| Field | What it tells you |
|---|---|
| Manufacturer and model | Which compressor it is; basis for parts and documentation |
| Serial number | Unique unit ID; often encodes the manufacture date |
| Voltage, phase, frequency | The power supply it needs (for example 460 V, 3-phase, 60 Hz) |
| RLA (rated load amps) | Current at rated conditions; used to size and check protection |
| LRA (locked rotor amps) | Starting current when the rotor is stalled |
| MCC or MOC (max continuous current) | Highest allowed continuous current on some models |
| Refrigerant | Which refrigerant the design is approved for |
| Oil type and charge | Lubricant (for example POE) and amount |
| Design pressures | Maximum working pressure on high and low side |
| Displacement or capacity | Swept volume or nominal capacity in cfm, tons or horsepower |
| Approvals | UL, CSA, CE or PED marks |
Field names differ by brand. Some give horsepower, some a nominal ton rating.
How do you read the model number?
Every manufacturer codes models differently. Typical patterns include a prefix for the compressor family, a number for the size or number of cylinders, letters for motor type or refrigerant range, and a suffix for options. Do not guess from other brands.
- Use the manufacturer’s model nomenclature in the product catalog or technical bulletin.
- For Copeland, Bitzer, Bock, Danfoss and other brands, look up the nomenclature in the official literature.
- Compare the nameplate to the unit’s documentation to confirm it is the original compressor and has not been swapped.
How do you find the manufacture date?
The serial number often includes the year and week or month, but the format is brand-specific and has changed over time. Use the manufacturer’s serial-number guide or ask the manufacturer’s technical support. Age matters because it affects the refrigerant, oil and parts available.
Why do RLA and LRA matter?
- RLA sets the basis for overload relays, motor protectors and wire sizing. A compressor drawing well above RLA at normal conditions is overloaded or failing; see compressor burnout.
- LRA is the starting inrush. It affects contactor and breaker choices, generator sizing and whether a soft starter or variable-speed drive is needed.
Check the electrical supply too: the voltage at the compressor terminals should be within the manufacturer’s tolerance, often plus or minus 10%.
What do refrigerant and oil fields mean for service?
The refrigerant on the plate is the one the design is approved for. Do not charge a different refrigerant without manufacturer approval; see A2L refrigerants explained for why. The oil type matters because mixing mineral, alkylbenzene, POE and PAG oils can cause lubrication and compatibility problems.
What should you record before ordering parts or a replacement?
- Photo of the full nameplate and the compressor installation.
- Model and serial number, exactly as printed.
- Voltage, phase, frequency, RLA and LRA.
- Refrigerant, oil type and operating range (suction and discharge pressures).
- Piping connections, mounting and motor type (hermetic, semi-hermetic, open drive).
What do you do when the nameplate is missing or unreadable?
Nameplates fade, get painted over or fall off. If the plate is damaged, try these steps in order.
- Check other markings. The serial number is often stamped on the housing as well as on the plate. Look near the terminal box and the base.
- Look at the system. The unit or condenser nameplate, the refrigerant label and the original submittals can fill in model, charge and electrical data.
- Check the oil and refrigerant. Do not guess. The oil type matters; see compressor oil types (POE, PAG, mineral) for why oils are not interchangeable.
- Photograph and measure. Record the connection sizes, mounting pattern and motor details. These help a supplier cross-reference a part.
- Ask the manufacturer. A serial number is usually enough for the maker to identify the exact model.
Once you have the data, copy it into your equipment records so it never has to be rebuilt. It also helps to know which family you are dealing with; the hermetic, semi-hermetic and open compressors guide explains how construction affects what can be serviced and replaced. For brand-specific model numbering, see Copeland compressors explained.
Frequently asked questions
What if the nameplate is missing or unreadable?
Look for stamped numbers on the compressor housing, check the equipment’s records or the system’s nameplate, and ask the manufacturer to identify it from the serial and physical features.
Is the nameplate the same as the equipment data plate?
No. The compressor has its own plate, and the larger unit (condensing unit, chiller or rack) has a separate one with different data.
Can I find specs online from the model number?
Usually yes, in the manufacturer’s selection tool or catalog. Confirm that the model still matches the unit in front of you.
SpecServis engineers in Ukraine work with compressors from several makers. We are looking for technicians and partners in Central Texas. See our open positions or partnership options.
