What Pressure Should R-22 Be?
Updated October 26, 2026
R-22 A1 Lower toxicity, no flame propagation
You have gauges on an older home air conditioner and a suction and liquid-line number you cannot quite place. The equipment makers published a running pressure for each R-22 unit, and that is what the ranges here come from.
Call a normal reading a fault and you remove or add refrigerant that was fine; miss a real fault and the compressor pays for it. Either mistake is expensive on a system you can no longer top off casually.
At 95°F outdoors, Goodman and Lennox tables list a running R-22 air conditioner at 73–85 psig suction (low side) and 212–258 psig liquid (high side), read at the service valves.[1][2][3] That spans 21 outdoor units, with Goodman's at 80°F/67°F indoor air.[1][2][3] Your unit's nameplate and charging information carry its own values.[2]
R-22 running pressures by outdoor temperature
Suction is read at the suction service valve and liquid at the liquid service valve. Each row spans every manufacturer table for that outdoor temperature.[1][2][3]
| Outdoor | Low side (suction) | High side (liquid) |
|---|---|---|
| 65°F 18°C | 65–79 psig 448–545 kPa | 130–178 psig 896–1,227 kPa |
| 75°F 24°C | 70–81 psig 483–558 kPa | 156–199 psig 1,076–1,372 kPa |
| 85°F 29°C | 72–82 psig 496–565 kPa | 175–227 psig 1,207–1,565 kPa |
| 95°F 35°C | 73–85 psig 503–586 kPa | 212–258 psig 1,462–1,779 kPa |
| 105°F 41°C | 75–89 psig 517–614 kPa | 239–291 psig 1,648–2,006 kPa |
| 115°F 46°C | 82–92 psig 565–634 kPa | 264–331 psig 1,820–2,282 kPa |
Goodman SS-GSC13 (5/15) covers 7 units at 80°F/67°F indoor air, three airflows each. Lennox 13ACD (505,366M, 01/08) covers 7 units with TXV and fixed-orifice tables, and Lennox HS26 (504,672M, 04/04) 7 more; HS26 lists no 115°F row, so that row draws on 21 tables instead of 28. Lennox lists values within ±10 psig liquid and ±5 psig suction.[1][2][3]
Every unit at 95°F (28 tables)
Goodman rows are at 80°F/67°F indoor air and the middle of the three listed airflows.
| Maker | Model | Type | Low side (psig) | High side (psig) | Source |
|---|---|---|---|---|---|
| Goodman | GSC130181G* | single-stage | 83 | 226 | SS-GSC13 p. 5 |
| Goodman | GSC130241F* | single-stage | 81 | 233 | SS-GSC13 p. 7 |
| Goodman | GSC130301** | single-stage | 81 | 256 | SS-GSC13 p. 9 |
| Goodman | GSC130361G* | single-stage | 83 | 245 | SS-GSC13 p. 11 |
| Goodman | GSC130421C* | single-stage | 84 | 219 | SS-GSC13 p. 13 |
| Goodman | GSC130481C* | single-stage | 84 | 220 | SS-GSC13 p. 15 |
| Goodman | GSC130601D* | single-stage | 80 | 219 | SS-GSC13 p. 17 |
| Lennox | 13ACD-018 | TXV | 82 | 219 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-024 | TXV | 83 | 236 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-030 | TXV | 79 | 233 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-036 | TXV | 83 | 252 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-042 | TXV | 81 | 241 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-048 | TXV | 80 | 229 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-060 | TXV | 80 | 243 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-018 | fixed orifice (RFC) | 82 | 218 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-024 | fixed orifice (RFC) | 82 | 232 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-030 | fixed orifice (RFC) | 79 | 237 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-036 | fixed orifice (RFC) | 83 | 247 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-042 | fixed orifice (RFC) | 82 | 240 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-048 | fixed orifice (RFC) | 80 | 227 | 13ACD 505,366M p. 18 |
| Lennox | 13ACD-060 | fixed orifice (RFC) | 81 | 239 | 13ACD 505,366M p. 18 |
| Lennox | HS26-018 | not stated | 78 | 223 | HS26 504,672M p. 14 |
| Lennox | HS26-024 | not stated | 79 | 226 | HS26 504,672M p. 14 |
| Lennox | HS26-030 | not stated | 76 | 223 | HS26 504,672M p. 14 |
| Lennox | HS26-036 | not stated | 73 | 223 | HS26 504,672M p. 14 |
| Lennox | HS26-042 | not stated | 78 | 227 | HS26 504,672M p. 14 |
| Lennox | HS26-048 | not stated | 75 | 216 | HS26 504,672M p. 14 |
| Lennox | HS26-060 | not stated | 76 | 232 | HS26 504,672M p. 14 |
R-22 head pressure: what pushes it up
The high-side gauge on a split system reads liquid-line pressure at the liquid service valve, and it follows the outdoor temperature. From 65°F to 115°F outdoors, it rose 121–176 psig across these tables.[1][2]
Indoor humidity adds to it: in Goodman's tables at 95°F, raising the entering wet bulb from 59°F to 71°F raised liquid pressure 35–41 psig.[1]
Carrier lists a dirty condenser coil, a failed fan motor and condenser air recirculation as causes of high pressure, and its R-22 units open the high-pressure switch around 400 psig.[5] DOE's diagnostic guide adds overcharge, non-condensables and a liquid-line restriction when the condensing temperature runs too far above outdoor air.[6]
R-22 suction pressure: indoor load and outdoor temperature
Suction rises with the wet bulb of the air entering the indoor coil. In Goodman's tables at 95°F outdoors and an 80°F indoor dry bulb, raising the wet bulb from 59°F to 71°F raised suction 17–18 psig on each unit.[1]
| Indoor wet bulb | Low side (suction) | High side (liquid) |
|---|---|---|
| 59°F | 66–73 psig 455–503 kPa | 187–227 psig 1,289–1,565 kPa |
| 63°F | 71–78 psig 490–538 kPa | 201–244 psig 1,386–1,682 kPa |
| 67°F | 77–85 psig 531–586 kPa | 212–258 psig 1,462–1,779 kPa |
| 71°F | 82–91 psig 565–627 kPa | 222–269 psig 1,531–1,855 kPa |
Outdoor temperature moved suction about as much in Goodman's tables, 17–18 psig from 65°F to 115°F. Lennox's tables moved less: 5–10 psig with a TXV and 12–20 psig with a fixed orifice, and HS26, listed only to 105°F, rose 4–6 psig.[1][2][3]
Across the three airflows Goodman lists, suction changed 3–4 psig and liquid 8–10 psig at 95°F.[1]
What the pressures mean in temperature
At 95°F outdoors, the 73–85 psig suction range is a 43.0–50.6°F saturation temperature, and the 212–258 psig liquid range is 105.4–119.4°F, 10–24°F above the outdoor air.[4] See the R-22 PT chart.
Standing pressure with the system off
With the system off long enough for the pressures to equalize, the gauges read the saturation pressure of the liquid refrigerant at its temperature. During the off cycle, refrigerant migrates toward the coldest part of the system, so the reading follows that spot's temperature rather than the outdoor air.[7] NIST notes that non-condensable gas can be diagnosed from its partial pressure while the system is off.[8]
| Off temperature | Standing (psig / kPa) |
|---|---|
| 65°F 18.3°C | 111 psig 767 kPa |
| 70°F 21.1°C | 121 psig 837 kPa |
| 75°F 23.9°C | 132 psig 912 kPa |
| 80°F 26.7°C | 144 psig 990 kPa |
| 85°F 29.4°C | 156 psig 1,073 kPa |
| 90°F 32.2°C | 168 psig 1,161 kPa |
| 95°F 35.0°C | 182 psig 1,253 kPa |
| 100°F 37.8°C | 196 psig 1,351 kPa |
| 105°F 40.6°C | 211 psig 1,453 kPa |
| 110°F 43.3°C | 226 psig 1,561 kPa |
| 115°F 46.1°C | 243 psig 1,674 kPa |
Servicing an R-22 system today
US production and import of HCFC-22 ended January 1, 2020 under the EPA Class II ozone-depleting-substance phaseout.[10] Recover the charge and repair leaks rather than topping off.
Readings that point to a problem
Faults show up as a pattern across suction, head pressure, superheat and subcooling, compared with the same system running normally.[8] NIST measured these patterns on a 2.5-ton R-410A heat pump with a TXV in cooling mode, and its report also reproduces Breuker and Braun's chart for a rooftop unit with a fixed orifice.[8]
| Fault | Suction | Head | Superheat | Subcooling |
|---|---|---|---|---|
| Undercharge, superheat still under 16°F | no change detected | lower | no change detected | lower |
| Undercharge, superheat above 16°F | lower | lower | higher | lower |
| Overcharge | no change detected | higher | no change detected | higher |
| Liquid-line restriction, superheat above 16°F | lower | lower | higher | higher |
| Low indoor airflow | lower | lower | no change detected | no change detected |
| Low outdoor airflow, superheat under 16°F | higher | higher | no change detected | lower |
| Low outdoor airflow, superheat above 16°F | lower | higher | higher | lower |
| Compressor valve leakage | higher | lower | no change detected | lower |
NIST split its results at 9°C (16.2°F) of superheat, where the TXV runs out of control range. A liquid-line restriction caused no detectable change below that point. Overcharge, low indoor airflow and compressor leakage never pushed superheat past it at the fault levels tested.[8]
| Fault | Suction | Head | Superheat | Subcooling |
|---|---|---|---|---|
| Refrigerant leak (undercharge) | lower | lower | higher | lower |
| Liquid-line restriction | lower | lower | higher | higher |
| Condenser fault (blocked coil) | higher | higher | lower | lower |
| Evaporator fault | lower | lower | lower | lower |
| Compressor valve leakage | higher | lower | lower | lower |
Neither NIST chart covers an overcharged fixed-orifice system. DOE's flowchart below does.
DOE's order of checks
DOE's Building America diagnostics guide works through the readings in order once the indoor coil's temperature split runs more than 3°F below its target, with separate charts for fixed-orifice and TXV systems.[6]
| Reading | Fixed orifice | TXV |
|---|---|---|
| Condensing temperature too far above outdoor air | Non-condensables, fouled condenser coil, overcharge or liquid-line restriction | Same |
| Evaporator saturation temperature too low | Liquid-line restriction, fouled evaporator coil or low charge | Same, or the TXV is out of adjustment |
| Low subcooling, low superheat | Expansion device overfeed or fouled evaporator coil | TXV overfeed: unsecured bulb or adjustment |
| Low subcooling, high superheat | Undercharge | Undercharge, or TXV underfeed: bad power element or adjustment |
| High subcooling, low superheat | Overcharge | Overcharge, or TXV overfeed |
| High subcooling, high superheat | Low outdoor temperature | Undercharge, or TXV underfeed |
DOE gives its limits as starting points. Its Table 3 lists a maximum condensing-over-ambient of 25°F above 12 SEER, 30°F at 10–12 SEER and 35°F below 10 SEER, and a minimum evaporator saturation temperature of 35°F, 40°F and 45°F alongside indoor wet bulbs of 62–63°F, 64–65°F and 66–67°F.[6] It adds that non-condensables or a liquid-line restriction also raise subcooling.[6]
Frequently asked questions
What should R-22 pressures be at 70, 80, 90 and 100°F?
Lennox's 13ACD tables list R-22 in 5°F steps: at 70°F, 67–80 psig suction and 148–174 psig liquid; at 80°F, 73–81 and 174–201 psig; at 90°F, 77–82 and 203–233 psig; at 100°F, 80–84 and 234–271 psig.[2]
What is normal R-22 head pressure?
What is R-22 standing pressure?
With the system off and equalized, it is R-22's saturation pressure at the refrigerant's temperature: about 132 psig at 75°F and 182 psig at 95°F.[4]
What should R-22 suction pressure be?
Can you still recharge a system with R-22?
Yes, but no new R-22 is produced: US production and import ended January 1, 2020.[10] Repair leaks and recover the charge rather than topping off.
How these numbers are calculated
Every operating range on this page comes from manufacturer tables, extracted from the PDFs by script rather than retyped, checked for consistent trends and spot-checked against the page images.
Goodman's SS-GSC13 spec sheet lists liquid ("Hi PR") and suction ("Lo PR") pressure at the service valves for each outdoor unit at four indoor dry bulbs (70–85°F), four wet bulbs (59–71°F), three airflows and six outdoor temperatures. We use the 80°F/67°F rows, the indoor conditions of the AHRI 210/240 AFull rating test (95°F outdoors), unless a section says otherwise.[9]
Lennox's 13ACD (with separate TXV and fixed-orifice tables) and HS26 manuals list typical pressures by outdoor temperature without stating indoor conditions. Saturation temperatures and standing pressures come from CoolProp 7.2.0.[1][2][3][4]
Sources
- [1]GSC13 Split System Air Conditioner, 13 SEER, R-22 (spec sheet SS-GSC13). Goodman. 5/15. https://apps.goodmanmfg.com/brochures/files/5711345664158SS-GSC13.pdf (accessed October 20, 2026). Expanded Cooling Data — R-22 liquid (Hi PR) and suction (Lo PR) pressures at the service valves, by outdoor temperature and indoor condition.
- [2]Merit Series 13ACD Units installation instructions 505,366M. Lennox. 01/08. https://www.lennox.com/dA/b1e4c32104/Lennox_13ACD_IOM.pdf (accessed October 20, 2026). Table 6. HCFC-22 Normal Operating Pressures, PDF p. 18 — R-22 typical liquid and suction/vapor operating pressures by outdoor temperature.
- [3]HS26 Series Units installation instructions 504,672M. Lennox. 04/04. https://www.lennox.com/dA/f9fb3f7ce3/Lennox_HS26_IOM.pdf (accessed October 20, 2026). Table 5. Normal Operating Pressures, PDF p. 14 — R-22 typical liquid and suction/vapor operating pressures by outdoor temperature.
- [4]CoolProp 7.2.0. CoolProp (I. H. Bell, J. Wronski, S. Quoilin, V. Lemort). https://coolprop.org/ (accessed October 2, 2026). Bell, I. H.; Wronski, J.; Quoilin, S.; Lemort, V. Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp. Ind. Eng. Chem. Res. 53, 2498–2508 (2014). https://doi.org/10.1021/ie4033999
- [5]Residential Air Conditioners and Heat Pumps Using R-22 and Puron Refrigerant: Application Guideline and Service Manual, Catalog No. 24-25-2SM. Carrier. 04/08. https://www.shareddocs.com/hvac/docs/1009/Public/07/24-25-2SM.pdf (accessed October 20, 2026). p. 13, High-Pressure Switch — high-pressure-switch cutout settings and high-head causes.
- [6]Measure Guideline: Air Conditioner Diagnostics, Maintenance, and Replacement (D. Springer, B. Dakin), NREL/SR-5500-56283. U.S. DOE Building America. March 2013. https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/measure_guide_air_cond_diagnostics.pdf (accessed October 20, 2026). Section 3.4 pp. 32–33, Table 3 p. 32, Figures 17–18 p. 33 — order-of-checks diagnostic flowcharts for fixed-orifice and TXV systems.
- [7]Scroll compressors SH090 to SH485, R410A: Application guidelines, AB243586442172en-US1301. Danfoss. https://assets.danfoss.com/documents/90219/AB243586442172en-US1301.pdf (accessed October 20, 2026). p. 31, off-cycle migration — refrigerant migrates to the coldest part of the system during the off cycle.
- [8]NIST Special Publication 1087, Cooling Mode Fault Detection and Diagnosis Method for a Residential Heat Pump (M. Kim, S. H. Yoon, W. V. Payne, P. A. Domanski). National Institute of Standards and Technology. October 2008. https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication1087.pdf (accessed October 20, 2026). Table 5.1(a) p. 40 and Table 5.2 p. 41, fault-direction charts; Section 5.4.1 p. 58 — residential heat-pump cooling-mode fault patterns.
- [9]AHRI Standard 210/240-2023 (2020), Performance Rating of Unitary Air-conditioning and Air-source Heat Pump Equipment. AHRI. 2023 (2020). https://www.ahrinet.org/system/files/2023-09/AHRI%20Standard%20210.240-2023%20%282020%29.pdf (accessed October 19, 2026)
- [10]Phaseout of Class II Ozone-Depleting Substances. US EPA. last updated April 1, 2026. https://www.epa.gov/ods-phaseout/phaseout-class-ii-ozone-depleting-substances (accessed October 2, 2026)