HVAC Decoder
Goodman Tonnage From Model Number
Where Goodman puts the capacity code, what each code means, and the readings that look like capacity but are not. Read out of 5 documents Goodman publishes itself, named further down with the date each was fetched.
Starting the decoder. The capacity tables below this box are already loaded, so you can read your code off them now.
Nominal capacity from a model number is a nameplate convention, not a measurement. Actual delivered capacity depends on the matched indoor unit, line set, airflow and conditions. Confirm against the data plate's BTU/h rating and the AHRI certificate for the matched system.
Goodman Capacity Codes and Tonnage
R-410A GSX and GSZ generation
Capacity sits at positions 6-8, the 3 digit group after the SEER digits. Example: GSX140361KA.
Transcribed from the manufacturer's own capacity legend for the Goodman / Amana scheme. The capacity, not just the position, is printed in a document this tool holds.
| Code | Nominal BTU/h | Tons | Code / 12 |
|---|---|---|---|
| 018 | 18,000 | 1.5 | same answer |
| 019 | 18,000 | 1.5 | 1.58, so the division is wrong here |
| 024 | 24,000 | 2 | same answer |
| 025 | 24,000 | 2 | 2.08, so the division is wrong here |
| 030 | 30,000 | 2.5 | same answer |
| 031 | 30,000 | 2.5 | 2.58, so the division is wrong here |
| 036 | 36,000 | 3 | same answer |
| 037 | 36,000 | 3 | 3.08, so the division is wrong here |
| 042 | 42,000 | 3.5 | same answer |
| 043 | 42,000 | 3.5 | 3.58, so the division is wrong here |
| 048 | 48,000 | 4 | same answer |
| 060 | 60,000 | 5 | same answer |
Table transcribed from Product Specifications SS-GSX14 (SS-GSX14, 1/19), published by apps.goodmanmfg.com, fetched 2026-07-24.
R-32 GLXS and GLZS generation
Capacity sits at positions 8-9, a 2 digit code rather than the older 3 digit one. Example: GLXS4BA3610AA.
The tonnage is the one the maker's own document prints for this capacity code; any BTU/h shown beside it is converted from that tonnage.
| Code | Nominal BTU/h | Tons | Code / 12 |
|---|---|---|---|
| 18 | 18,000 | 1.5 | same answer |
| 24 | 24,000 | 2 | same answer |
| 30 | 30,000 | 2.5 | same answer |
| 36 | 36,000 | 3 | same answer |
| 42 | 42,000 | 3.5 | same answer |
| 48 | 48,000 | 4 | same answer |
| 60 | 60,000 | 5 | same answer |
Table transcribed from Product Specifications SS-GLXS4B-R32 (SS-GLXS4B-R32, 03/26), published by goodmanmfg.com, fetched 2026-07-24.
R-22 GSC13 and GSH13
Capacity sits at positions 6-8, the 3 digit group after the SEER digits 13, per Goodman's own SS-GSC13 nomenclature. Example: GSC130361AA.
The tonnage is the one the maker's own document prints for this capacity code; any BTU/h shown beside it is converted from that tonnage.
| Code | Nominal BTU/h | Tons | Code / 12 |
|---|---|---|---|
| 018 | 18,000 | 1.5 | same answer |
| 024 | 24,000 | 2 | same answer |
| 030 | 30,000 | 2.5 | same answer |
| 036 | 36,000 | 3 | same answer |
| 042 | 42,000 | 3.5 | same answer |
| 048 | 48,000 | 4 | same answer |
| 060 | 60,000 | 5 | same answer |
Table transcribed from GSC13 Energy-Efficient Split System Air Conditioner 13 SEER / R-22 (Product Specifications) (SS-GSC13, 5/15), published by apps.goodmanmfg.com, fetched 2026-10-01.
The Goodman codes that dividing by 12 gets wrong
The usual shortcut is that a capacity code is the nominal BTU/h divided by 1,000, so dividing it by 12 gives the tonnage. Goodman prints 5 codes where that arithmetic disagrees with Goodman's own table, and the table is what the equipment is sold against:
| Code | Goodman prints | Code / 12 gives |
|---|---|---|
| 019 | 1.5 tons | 1.58 |
| 025 | 2 tons | 2.08 |
| 031 | 2.5 tons | 2.58 |
| 037 | 3 tons | 3.08 |
| 043 | 3.5 tons | 3.58 |
These are not derivable, only transcribable, which is why this decoder carries Goodman's printed table rather than a formula. If you meet one of these codes in the field, arithmetic will land you between two real sizes, and the printed table is the only thing that resolves it.
Worked example: Goodman GSX140361KA
Capacity code 036 at characters 6-8 of GSX140361KA: 36,000 BTU/h, which is 3 tons at 12,000 BTU/h per ton. The capacity code in the Goodman/Amana split layout. SS-GSX14 rates GSX140361** at 36,000 BTU/h in the row it heads "Nom Cool (BTU/h)", so both figures are transcribed rather than calculated from the code.
- Efficiency: 14 SEER. SS-GSX14 prints 14 as "14 SEER" under "Efficiency" for the digits in the GSX14 prefix: the series' nominal SEER, not this unit's rating.
- Refrigerant: R-410A. Goodman position 3 "X Condenser R-410A" per SS-GSX14.
- Product type: AC condenser. Position 3 unit type X.
Goodman has 3 documented layouts: R-410A GSX and GSZ generation reads capacity at positions 6-8; R-32 GLXS and GLZS generation reads capacity at positions 8-9; R-22 GSC13 and GSH13 reads capacity at positions 6-8. They put the capacity in different places, so a rule written for one and applied to the other is how a right-looking number ends up under the wrong heading.
What is specific to Goodman
Goodman equipment in the decoder
The decoder reads or identifies these Goodman lines; each one says what it rests on. Open an example to see the decoder's full answer for it.
| Line | Example model | What the decoder reads | Document |
|---|---|---|---|
| Goodman GSC13/GSH13 R-22 split system | GSC130361AA | 3 tons (36,000 BTU/h) | SS-GSC13 |
| Goodman/Amana ASPT air handler | ASPT49D14AC | An air handler: 4 tons (48,000 BTU/h) | SS-GASPT |
| Goodman AWUF/AWUT wall-mount air handler | AWUF180516B | An air handler: 1.5 tons (18,000 BTU/h) | SS-GAWUF |
| Goodman GPGM3 packaged gas/electric unit (R-410A) | GPGM34808041 | A packaged unit: 4 tons (48,000 BTU/h) | SS-GPGM3 |
| Goodman GPGM3/GPDM3/GPUM3 packaged unit (R-32) | GPGM33608031AA | A packaged unit: 3 tons (36,000 BTU/h) | SS-GPGM3_GPUM3-R32 |
| Goodman GR9S/GD9S gas furnace | GR9S800603BN | A gas furnace: its size field is heating input, so no cooling tonnage is read | SS-GR9S80_GD9S80-R32 |
| Goodman PHKJ package heat pump | PHKJ024-1A | A packaged unit: identified; its maker's document prints no model number legend, so no size is read | RP - 234J |
- Goodman GMVC96 gas furnace: identified as a gas furnace by its maker's form; its size field is heating input, not cooling capacity, so no tonnage is read.
CPSC recall notices naming Goodman
Hazard, in the notice's words: “A power interruption in the heat pump can result in the product providing heat when the power resumes, despite the thermostat being in cooling mode, posing a risk of excessive heat exposure to consumers.”
Hazard, in the notice's words: “The labels found on the serial plate have incorrect electrical information that could result in installers and servicers using undersized wiring or incorrect fuse/circuit breaker parts, posing a fire hazard.”
Hazard, in the notice's words: “The blower motor is not grounded, posing an electrical shock hazard to individuals servicing the units”
Hazard, in the notice's words: “The pull-out disconnects may not disable power to the air handler, posing an electrical shock hazard to individuals servicing the units.”
Hazard, in the notice's words: “The serial plates on the units contain inaccurate information that could result in the use of undersized installation wiring, posing a fire hazard.”
Hazard, in the notice's words: “Heat exchangers in the furnace can crack.”
Whether a particular unit is inside a recall depends on the models and serials the notice lists. The Goodman serial number lookup checks a unit against the notices.
Amana, same family as Goodman
Amana is in Goodman's family. These are Amana's lines; each one says what it rests on.
| Line | Example model | What the decoder reads | Document |
|---|---|---|---|
| Goodman/Amana ASPT air handler | ASPT49D14AC | An air handler: 4 tons (48,000 BTU/h) | SS-AASPT |
| Amana VTAC | AVH093H25AXXX | An Amana VTAC single package vertical unit: 0.75 tons (9,000 BTU/h) | MC-VTAC 10-20 |
Other CPSC recall notices naming Amana
Notices that also name Goodman are listed above.
Hazard, in the notice's words: “The serial plates on the units have inaccurate information that could result in installers and servicers using undersized wiring, posing a fire hazard.”
Whether a particular unit is inside a recall depends on the models and serials the notice lists. The Amana serial number lookup checks a unit against the notices.
Models this decoder refuses rather than guesses
An undocumented code publishes nothing. Each of these would produce a plausible number by general arithmetic, and the decoder returns no match instead, because no Goodman document supports it.
| Model | What the decoder returns | Why |
|---|---|---|
| GSX140091KA | no match | 009 sits on the universal ladder but appears in no Goodman or Amana capacity table, so no tonnage is published. |
| GSX140151KA | no match | 015 is the same case as 009: arithmetically valid, documented by neither brand. |
The Goodman documents behind this page
Published by apps.goodmanmfg.com. Fetched 2026-07-24. Covers the R-410A GSX generation: the Nominal Capacity table including every off-ladder code, corroborated inside the same document by its Product Specifications rated-BTU/h table.
Published by partnerlinkmarketing.goodmanmfg.com. Fetched 2026-10-03. Covers the communicating 16 and 18 SEER condensing units and heat pumps with a fourth prefix letter (ASXC, GSXC, ASZC, GSZC), listed by revision row with their capacity codes.
Published by goodmanmfg.com. Fetched 2026-07-24. Covers the R-32 GLXS and GLZS layout: position 1 G for Goodman Brand, position 2 L for R-32 Splits System, Nominal Capacity at positions 8-9, and the Efficiency (SEER2) Nominal tier ranges. This is the document whose nomenclature legend contradicts its own rated-capacity table.
Published by goodmanmfg.com. Fetched 2026-08-27. Covers the R-32 HEAT PUMP half of the GLXS/GLZS layout, and it is cited for one thing: its Nominal Capacity legend prints "30 - 2½ tons", which is one of the independent readings that refute SS-GLXS4B-R32's "30 - 2 Tons". Its capacity codes are two digits (18, 24, 30, 36, 42, 48, 60) and its own model list uses two digits to match (GLZS4BA3010A*). It sources no position claim this tool does not already take from SS-GLXS4B-R32.
Published by apps.goodmanmfg.com. Fetched 2026-10-01. Covers the GSC13 and GSH13 R-22 split layout on page 2: G Goodman, S Split System, C Condenser R-22 and H Heat Pump R-22, 13 13 SEER, and Nominal Capacity 018 to 060 in tons.
Frequently asked questions
How do I find the tonnage of a Goodman unit from the model number?
Read the capacity code: on Goodman it sits at positions 6-8, the 3 digit group after the SEER digits. On GSX140361KA that code is 036, which is 36,000 BTU/h, or 3 tons, because one ton of cooling is 12,000 BTU/h. Use the OUTDOOR unit's model number for system cooling capacity; the indoor air handler or coil carries its own number. This position comes from Goodman's own SS-GSX14, not from a third-party chart.
Can I just divide the Goodman capacity code by 12?
Not on every code. Goodman prints 5 capacity codes where that division gives the wrong answer: 019 is 1.5 tons where dividing gives 1.58, 025 is 2 tons where dividing gives 2.08, 031 is 2.5 tons where dividing gives 2.58, 037 is 3 tons where dividing gives 3.08, 043 is 3.5 tons where dividing gives 3.58. Those values come from Goodman's own printed table rather than from arithmetic, which is the whole reason the table exists. On every other code in the table the division does work.
Where is the model number on a Goodman unit?
On the data plate on the outdoor condenser, where Goodman prints the model above the serial. It is labeled M/N, MODEL or MODEL NO., usually printed directly above or beside the serial number. The model number describes what the unit is, including its capacity. The serial number describes when it was built and carries no capacity information at all.
Which Goodman document is this based on?
Product Specifications SS-GSX14 (SS-GSX14, 1/19), published by apps.goodmanmfg.com and fetched 2026-07-24, which covers the R-410A GSX generation: the Nominal Capacity table including every off-ladder code, corroborated inside the same document by its Product Specifications rated-BTU/h table. Service and Troubleshooting ASXC, DSXC, and GSXC Condensing units, ASZC, DSZC, and GSZC Split System Heat Pumps (RS6200007r27, May 2023), published by partnerlinkmarketing.goodmanmfg.com and fetched 2026-10-03, which covers the communicating 16 and 18 SEER condensing units and heat pumps with a fourth prefix letter (ASXC, GSXC, ASZC, GSZC), listed by revision row with their capacity codes. Product Specifications SS-GLXS4B-R32 (SS-GLXS4B-R32, 03/26), published by goodmanmfg.com and fetched 2026-07-24, which covers the R-32 GLXS and GLZS layout: position 1 G for Goodman Brand, position 2 L for R-32 Splits System, Nominal Capacity at positions 8-9, and the Efficiency (SEER2) Nominal tier ranges. This is the document whose nomenclature legend contradicts its own rated-capacity table. Product Specifications SS-GLZS4B-R32 (SS-GLZS4B-R32, 07/26), published by goodmanmfg.com and fetched 2026-08-27, which covers the R-32 HEAT PUMP half of the GLXS/GLZS layout, and it is cited for one thing: its Nominal Capacity legend prints "30 - 2½ tons", which is one of the independent readings that refute SS-GLXS4B-R32's "30 - 2 Tons". Its capacity codes are two digits (18, 24, 30, 36, 42, 48, 60) and its own model list uses two digits to match (GLZS4BA3010A*). It sources no position claim this tool does not already take from SS-GLXS4B-R32. GSC13 Energy-Efficient Split System Air Conditioner 13 SEER / R-22 (Product Specifications) (SS-GSC13, 5/15), published by apps.goodmanmfg.com and fetched 2026-10-01, which covers the GSC13 and GSH13 R-22 split layout on page 2: G Goodman, S Split System, C Condenser R-22 and H Heat Pump R-22, 13 13 SEER, and Nominal Capacity 018 to 060 in tons. Every capacity value in the capacity tables above traces to one of those documents, and each is named with the date it was fetched so you can pull it yourself. The sizes in the equipment table are read from the document named in its Document column, listed on this page's source receipt.
Is the decoded tonnage the size I should install?
No. Nominal tonnage is what the unit was built to deliver, not what the building needs, and the old unit may have been oversized or sized before insulation and window changes. Treat it as a starting clue and run a load calculation before matching a replacement. Actual delivered capacity also depends on the matched indoor unit, line set, airflow and conditions.
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Got a central system's tonnage? Check it against the house's load.
The old unit's nominal size is a clue, not a load calculation. Oversized systems short-cycle and dehumidify poorly. For central equipment that conditions the whole house, run the numbers before you match a replacement. A PTAC, a single package vertical unit, a room air conditioner or one unit of a VRF system conditions a room or a zone, which this load calculator does not size.