The R-134a pressure-temperature table on this page is looked up from a named datasheet, not computed here, and the charge check under it reads that table. The charge check's method, bands, airflow precondition and hazards come from the charging documents listed after the datasheet, the same documents the superheat calculator's receipt names. The charge check under the table can also print the compressor maker's statements for R-134a: the station the suction line temperature was taken at, with what the publishers state there and receiver charging on a receiver system. Those statements are quoted from the 3 publisher documents listed after the charging documents; a quoted sentence is cited beside itself with the publisher, the document as the publisher identifies it, and the page where the sentence is quoted.
- R-134a pressure-temperature table
- Arkema Forane 134a and iGas USA charts, both NIST REFPROP 9.0 reference data. Its cross-checks, and which of them are separate publishers, are marked under the table above.
- CEC-400-2022-010-AP, Reference Appendix RA3 Table RA3.2-1 (Installer Testing at Final)
- The pass and fail bands, and the conditions they hold under. Variable metering devices are judged on subcooling to plus or minus 3 degrees F of the manufacturer-specified target; fixed orifices on superheat to plus or minus 5 degrees F of the target for the conditions; the metering device itself against the manufacturer's specification or 4 to 25 degrees F. The same table states the envelope those tolerances hold inside, and the engine checks it before applying any of them: outdoor dry-bulb 55 to 115 degrees F on a fixed orifice and 55 to 120 on a variable metering device, with return-air dry-bulb at or above 70. The Installer row is the one shipped, never the looser ECC and HERS Rater row beside it.
- CEC-400-2022-010-AP, Reference Appendix RA3 Table RA3.2-2 (target superheat)
- The target superheat grid for fixed-orifice charging, indexed by indoor wet-bulb and outdoor dry-bulb. Cells are machine-parsed from the appendix rather than transcribed by hand, and a sample was compared against a manufacturer grid from a different publisher as an outside check. The comparison is disclosed rather than claimed as proof: two publishers printing the same targets can inherit one lineage.
- CEC-400-2022-010-AP, Joint Appendix JA6.1.6.3 (the airflow precondition)
- Why this tool checks airflow before it grades a charge, and why it will refuse to grade one. Items 1 to 3 each require that the minimum airflow requirement from item 4 is satisfied before their charge criteria are valid, so a superheat or subcooling reading taken on restricted airflow is not a charge measurement. The direction depends on the metering device: on a fixed orifice a starved evaporator drives superheat DOWN and widens the temperature split, which reads like an overcharge, while on a TXV the valve holds superheat and the fault shows in suction pressure and subcooling. That is the confound the whole air-side check exists to separate.
- Carrier PH5SAN5, Carrier SM10-R454B-03, Carrier 25SCA5, Goodman IOG-4048C, ICP 428 01 5106 00, Trane 88-M5MHWUN-1A-EN, Rheem RD16AY, and Bosch service literature
- Which charging method a given machine actually permits, and when the manufacturer says not to check the charge at all. Carrier PH5SAN5 (R-454B installation instructions) states the outdoor window it publishes for checking charge and states the airflow precondition directly; Trane and Bosch reach the same place in their own words. Carrier SM10-R454B-03 supplies the sentence defining what a dashed cell on a superheat grid means, which is an instruction not to charge on that reading. Goodman IOG-4048C and the ICP grid (428 01 5106 00) supply the dashed regions themselves. Trane 88-M5MHWUN-1A-EN is the ductless installer guide behind the mini-split fork: it publishes no superheat or subcooling procedure at all, which is why this tool declines to issue a reading-based charge verdict on ductless equipment, and we state that as evidence about THAT guide rather than about every ductless machine. Rheem RD16AY supplies the evaporator-icing instruction the engine will not charge through. Where these documents route the technician to a weigh-in or to the unit’s own charging procedure, this tool routes there too instead of grading a reading the manufacturer does not charge from.
- The per-machine charge-target corpus (registered manufacturer books, cited by form number)
- Where a specific machine's target subcooling is written, quoted from that manufacturer's own book with its form number. 15 documents across 7 brand families are registered and content-pinned: Carrier (SM10-R454B); Goodman (IOD-4064A, IOG-4048C, IOG-4064A); York (5391577-UIM-B-0718, 6411591-UIM-B-0824, 6694740-UIM-B-1025); Lennox (100108); Nortek (708921E, 7094080); Rheem (92-104921-25-04, 92-110354-01-01); Trane (11-AC22D1-1, 18-AC94D1-4-EN, 4TWX6060E-SF-1A). The tool publishes NO target subcooling value of its own from any of them. What it publishes is WHERE the figure lives on that machine, what that manufacturer calls it, the verbatim sentence it is read from, and which model series that sentence covers - so a claim read out of one book stops at the machines that book's own cover names. Where a book's current revision cannot be established, or where its own pages disagree, the value stays withheld and the reason is printed instead.
- York ST-022-12, Figures 1 and 2 (example charging charts)
- The dose and the wait in the protocol loop: add or remove charge in one-ounce increments and let the system stabilize for ten minutes, repeating until the reading is in band. York prints these as examples and says so, and the tool passes that scope through rather than presenting the increment as a universal specification.
- Rheem RD16AY / RD18AY section 5.7, and Lennox 13ACX 506374-01 page 20
- The two hazards this engine will not charge through. Rheem's instruction covers running a system at a suction pressure that will ice the evaporator coil, and it is quoted with its own scope, which names cooling mode. Lennox states the low-superheat floor below which refrigerant must not be added, because liquid reaching the compressor is damage happening in that instant rather than a charge level. Both are carried on every branch, including the branches where a charging instruction is being withheld.
- Copeland discharge-temperature guidance, and Proctor Engineering on airflow and capacity
- The two checks that sit beside the charge rather than inside it. Copeland's discharge-line temperature limit is what the tool watches for a compressor running hot. Proctor's finding that a passing temperature split can also mean low airflow AND low capacity together is why a passing split is not treated as proof the air side is healthy.
- Copeland, AE4-1344 R21
- Application Guidelines for Copeland RFT, RRT, RST Compressors. June 2024. Names, of the fluids this site carries, R-134a, R-290, R-404A, R-448A and R-449A. The sentences this site holds from it are at page 6 (taken from the file's own text rather than the rendered page). Fetched 2026-09-05 from webapps.copeland.com. https://webapps.copeland.com/online-product-information/Publication/LaunchPDF?Index=AEB&PDF=1344
- Copeland, AE22-1182 R26
- Liquid Refrigerant Control in Refrigeration and Air Conditioning Systems. June 2024. Its superheat statements name no particular refrigerant, so it is cited wherever a commercial fluid is read. "A well designed, durable, and efficient compressor for refrigeration, air conditioning, or heat pump duty is primarily a vapor pump designed to handle a small quantity of liquid refrigerant and oil." The sentences this site holds from it are at pages 9 to 10 (read by rendering the page). Fetched 2026-09-05 from webapps.copeland.com. https://webapps.copeland.com/online-product-information/Publication/LaunchPDF?Index=AEB&PDF=1182
- Copeland, AE-105 R3 (5/18)
- Refrigeration Manual Part 5, Installation and Service. Revision 3, May 2018. Its superheat statements name no particular refrigerant, so it is cited wherever a commercial fluid is read. Its measuring sentence sits under "5. Charging By Superheat", which opens: "On small unitary systems equipped with capillary tubes, the operating superheat may be used to determine the proper charge." Its receiver-charging statements are general. The sentences this site holds from it are at page 74 (taken from the file's own text rather than the rendered page) and page 75 (taken from the file's own text rather than the rendered page). Fetched 2026-09-05 from media.copeland.com. https://media.copeland.com/ff6556eb-dbad-4757-8ef4-b16d00377e59/AE105-Installation%20and%20Service.pdf
The table values are looked up and interpolated from the datasheet within its disclosed tolerance, not measured here. The rack statements are quoted, not computed: a publisher's own conditions print on the adjacent line, and a document revised after the fetch date shown is not reflected until it is fetched again. The equipment's own literature has final say over any figure on this page.