Air Conditioner Compressor & Refrigerant Pressure Readings

HVAC refrigerant pressures, compression ratios, quantities, boiling points, chemical formulas
Global Warming Impact GWP & ODP data

Definition of Air Conditioner High Side and Low Side Pressures

Let's explain "low-side" and "high-side" air conditioner compressor motor pressures and what they mean.

Air conditioning service manuals and training refer to:

• Low-side air conditioner compressor motor pressure:
  
  This is the pressure in the air conditioner's refrigerant suction line (low side pressure during compressor operation) and this will be a relatively low number, often less than 100 psi.
  
  During operation, refrigerant gas is returning to the compressor from the cooling (evaporator) coil in this line.
  
  If we connected the suction line directly to a sealed vacuum test gauge we'd actually find that the compressor could pull an actual vacuum on the line.
  
  The low-side of an air conditioning system is always located inside of the space to be cooled, or inside of an air handler which moves air through the space to be cooled.
  
  By lowering the pressure in the cooling coil located on the "low side" of the air conditioning system, the compressor permits liquid refrigerant to be discharged into the cooling coil where the change of refrigerant state from a liquid to a gas absorbs heat and brings the cooling coil to the proper operating temperature.
  
  The LOW SIDE of a refrigeration system is the low-pressure and low temperature half of the system. Normally this is the indoor air handler - located inside the space that is to be cooled by bringing indoor air to operating temperature. (For a refrigerator this is typically 38 to 45 °F.)

• High-side air conditioner compressor pressure:
  
  Output (high side pressure during operation) is the pressure of the compressed refrigerant gas as it leaves the compressor motor. In other words, refrigerant gas returns to the compressor through the suction line from the cooling coil (which is cooling building air).
  
  The low-pressure refrigerant gas is compressed to a high-pressure refrigerant gas inside the compressor motor. This high temperature refrigerant gas is then cooled down to condense into a refrigerant liquid before it is returned indoors to the air handler and evaporator coil to be used to cool building air. (Thus we get the name "condensing coil" and "condensing unit" or "condenser" for the outside half of an air conditioning system.)
  
  The high side components of an air conditioning system, such as the compressor, condensing coil, and fan unit used to cool the condensing coil are located outside of the conditioned or refrigerated space, and will be immersed in air at ambient outdoor temperature, say 72 °F.
  
  Here is where the magic of air conditioning occurs. As long as the compressor can produce a temperature in the outdoor condensing coil which is above ambient outdoor air temperature, heat will flow from the condensing coil into outdoor air (for example outdoor air blown across the condensing coil by a fan).
  
  If you studied thermodynamics in high school you learned that heat always flows from the warmer to the cooler material. The effect is to transfer heat gathered in the indoor or conditioned space into outdoor air.
  
  The HIGH SIDE of a refrigeration system is at high temperature and higher (refrigerant) pressure and will always be above ambient temperature. So in a cooling system it will be located outside in order to transfer heat to the outdoor air. A heat pump designed to pump heat into a building will, of course, reverse these roles when in heating mode.

Tricks of the Trade - for Low-Budget HVAC Refrigerant Line Vacuum Tool

On my own graduation from HVAC school the instructor suggested that since most of the time when people are tossing out an old refrigerator the problem was electrical rather than the compressor, we should look for an old Frigidair refrigerator and salvage its comporessor motor.

Indeed I did just that and for years we used to use an old Frigidaire™ rotary-design compressor motor as our vacuum pump when we needed to get the air out of a refrigeration system prior to charging it with new refrigerant. - Daniel F.

Typical HVAC Refrigerant Pressures

Typical residential air conditioning refrigerant pressures vary depending on the model, compressor motor size and design, and the refrigerant used.

The design pressures may be provided on labels attached to the equipment but the actual air conditioner operating pressure will vary in part as a function of the incoming air temperatures.

"Charging Charts" (such as the commercial unit charging chart shown here) are provided in service manuals to determine the target suction vacuum (negative) pressure and output pressure for a given compressor motor.

Use of the charging chart for the specific compressor is the correct way to service it. The following example pressures are based on "rules of thumb" that get you in the right "ballpark" if no charging chart is at hand.

Example of actual air conditioner compressor high side output pressure:

Using R-22 refrigerant and assuming an outside air temperature of 85 °F called for 120 °F inside the compressor (add 35 °F to incoming air temperature) and an output high-side compressor pressure of about 260 psi.

Example of actual air conditioner low side input or suction line pressure during operation:

Low-side pressure during normal operation of the same compressor model and refrigerant and the same outdoor air temperature of 85 °F called for 45 °F temperature entering the compressor (subtract 40 °F from incoming air temperature) which on the service chart indicates that the incoming or suction line pressure would be about 75 psi.

Example of a more theoretical air conditioner or heat pump pressure and temperature at the compressor and at the cap tube or thermostatic expansion valve: 

During normal operation: at an outdoor temperature of 72 °F, liquid refrigerant (R12 for example) leaving the outdoor condensing coil and entering the cap tube or TEV might be at 100 psi and 95 °F.

These numbers vary by changes in ambient temperature, compressor model, and refrigerant gas used.

On the low side of the TEV or cap tube (in the cooling coil in the air handler) where the liquid refrigerant is changing state to a gas, it may be cooled down to 10 °F. and by the time the refrigerant leaves the cooling coil (evaporator coil) and gets back to the compressor motor it will be all vapor and may be at just 15 psi. [R12 refrigerant changes from liquid to vapor at 14.6 psi at 10 °F.]

Air Conditioner or Heat Pump Refrigerant Equalization Pressure - System-OFF refrigerant pressures

When you measure heat pump or cooling system pressures makes as much difference as where you measure it. When an air conditioning or heat pump system has turned off and been off for some time (30 minutes or more) pressures equalize throughout the system between the high and low sides.

At that point the refrigerant pressure in both the high side and low side of the air conditioner or heat pump system will be in accordance with the ambient air temperature and the properties of the particular refrigerant gas present.

The static or equalized system refrigerant pressure will be defined by the refrigerant gas type (which defines its boiling point and pressure at various temperatures).

For example with that cute old R12 refrigerant, as long as there is just about any refrigerant in the system - enough so that there is some liquid refrigerant, i.e. it's not all just gas) then in equalized condition at 70 psi ambient temperature the refrigerant pressure will be 70 psi.

With a temperature correction chart you can read the static or equalized refrigerant pressure for any refrigerant gas and the actual ambient temperature.

Reminder: this refrigerant gas behavior means that if you use pressure test gauges to measure the refrigerant pressure in the static or equalized air conditioning or heat pump system, the gauges only tell you the refrigerant pressure, not the quantity of refrigerant that is present in the system.

See GAUGE, REFRIGERATION PRESSURE TEST

Typical HVAC Compressor Motor Compression Ratios

What is the normal compression ratio at an AC or heat pump compressor/condenser unit?

A reader asked us by private email:

I have a 3 ton R22 rooftop heating/cooling home HVAC system failure (no heat right now).

AC mechanic says compression ratio is 1:1 (should be 3:1 or 4:1) and AMP draw is 5.5 rather than required 20.

The technician says that my compressor unit is bad and should be replaced.

How did she figure out the compression ratio for my unit?

Does a low compression ratio at my compressor/condenser unit always mean that it needs to be replaced? - Milton Silva

Normal HVAC compression ratios range from 2.3:1 to 3.5:1

BUT check for improper refrigerant charge and for a bad TEV before replacing an air conditioner or heat pump compressor due to compression ratio

To determing the current compression ratio for an A/C or heat pump compressor motor the technician measures the high side pressure and the low side "suction" pressure.

But another step is needed.

To calculate accurate compressor compression ratio the proper computation requires that we add the standard atmospheric pressure at sea level (1 ATM = 14.7 psi) to both the high side output or discharge and to the low side suction or input to the compressor.

And even though the low side pressure is "negative" or "suction" we treat it as a positive number in computing the compression ratio of the compressor motor.

HVAC Compressor Compression Ratio CR = (High side or discharge pressure + 14.7 psi) ÷ (Low side or suction pressure + 14.7 psi)

In this case since we're only looking for the compression ratio - what the compressor motor is capable of producing - we don't need to adjust for ambient temperature or other factors.

Example:

Using our test gauge set we measure 230 psig on the high side of the unit, and we measure 66 psig on the low side or suction side of the compressor unit.

CR = (230 + 14.7) ÷ (66 + 14.7)

CR = (244.7 psig) / (80.7 psig)

CR or Compression Ratio = 3.03 - this is within normal range for an HVAC compressor unit.

Causes of abnormally low compression ratios

If the AC compressor isn't compressing, the problem is typically internal, a worn compressor piston or a failed valve.

As your compressor is typically a sealed unit, repair isn't feasible. The unit gets replaced.

Watch out: before replacing the compressor,be sure the cause isn't something else easier and less costly to repair.

• Check theTEV - Thermostatic Expansion Valve operation.
  
  An expansion valve that sticks wide open will also give low compression ratios, lower current draw.
• Check the refrigerant charge Level
  
  Abnormal compressio ratios can be also an effect of refrigerant overcharge (which also risks liquid slugging and compressor motor damage).

More About Abnormal Residential Air Conditioner Compressor Pressures

Put another way, high temperature or a low compression ratio (high pressure on the air conditioner low side or low pressure on the high side) is a sign of a problem.

If pressure on the high side is very low the cause may be one of the problems we listed just above.

If pressure on the high side is abnormally high, we may have a TEV that's stuck closed (the low side pressure remains low or abnormally low) or if the TEV opens, low side pressure might increase as well, and we may exceed the operating temperature and pressure of the system.

The Low side temperature must be low enough to get transfer of heat from the indoor air into the evaporator coil. The High Side temperature must be high enough to get transfer of heat into the outdoor air.

• See SEER RATINGS & OTHER DEFINITIONS for additional definitions of the high side and low side of an air conditioning system.
• See COMPRESSOR CONDENSER for an explanation of how and why high side and low side pressures in the cooling system enable an air conditioner to move heat from indoors to outdoors.
• See OPERATING TEMPERATURES HVAC for a discussion of the typical temperatures at which various types of cooling systems operate.

If your air conditioning or heat pump system has lost its cooling capacity or won't start

see REPAIR GUIDE for AIR CONDITIONERS.

Comparison Table of Refrigerant Gas Properties

Notes to the table above

1. GWP = Global Warming Potential, relative contribution to global warming by contributing to greenhouse gases that trap heat in the earth's atmosphere. CO₂ (Carbon dioxide) has a GWP of 1.0.
   
   By 2025, high Global Warming Potential (GWP) refrigerants with a GWP of over 750, will be banned together along with HVACR equipment that uses that gas. Note that GWP ratings are controversial.
   
   ODP = Ozone Depletion Potential - relative damage to the earth's ozone layer.
   
   ODP is defined as the total amount of ozone destroyed by that substance compared with the amount of ozone that would be destroyed by the same mass of CFC-11 = Freon-11 = R-11.
   
   Combustible or flammable: refrigerants are rated as
   1 - not flammable,
   2L - very low flammability,
   2 - low flammability,
   3 - high flammability
   
   - Source:
   ASHRAE: ASHRAE Standard 34 describes a shorthand way of naming refrigerants and assigns safety classifications based on toxicity and flammability data
   ASHRAE Standard 15 establishes procedures for operating equipment and systems when using those refrigerants.
   
2. R404A, commercial use banned after 2020 is replaced by R448A, R449A, R452A, R407H.
3. R290 PT Chart, A-Gas, Units 7 & 8 Gordano Court Serbert Close Portishead, Bristol BS20 7FS UK, +44 1275 376600 Offices world wide, Website: www.agas.com, retrieved 2020/02/10 original source: https://www.agas.com/media/2422/r290-propane-pt-chart.pdf
   
   Linde, R290 REFRIGERANT GRADE PROPANE [PDF] Linde AG Linde Gases Division, Seitnerstrasse 70, 82049 Pullach, Germany Phone +49.89.7446-0, Fax +49.89.7446-1230, www.linde-gas.com/refrigerants, refrigerants@lindegas.com retrieved 2021/12/22 original source: http://hydrocarbons21.com/files/refrigeration_R290.pdf
   Excerpt:
   
   R290 is the common name for high purity propane (C3H8) suitable for use in the refrigeration and air conditioning industry. It is also known as CARE® 40.
4. R490 PT Chart, A-Gas, op. cit. retrieved 2020/02/10 original source: https://www.agas.com/media/2405/r404a-pt-chart.pdf
5. R407 Data, Daikin Chemical Europe GmbH Am Wehrhahn 50 40211 Düsseldorf, Germany Phone: +49 211-179225-0 Fax: +49 211-179225-39 daikinchem.de, retrieved 2020/02/10 original source: https://www.daikinchem.de/sites/default/files/pdf/Refrigerants/Daikin_R407H_Handling_Brochure_EN.pdf
   
   R407H: zeotropic mixture of 32.5 weight% R32, 15 % R125, and 52.5% R134a. It is a drop-In refrigerant for R404A / R507 and a retrofit refrigerant for R22.
6. R448A Data, (N40) Pressure & Temperature, FSW op. cit. retrieved 2020/02/10 original source: https://www.fsw.uk.com/sites/www.fsw.uk.com/files/r448a-n40-pt-chart.pdf
   
   Alternative Chart: R448A Data Honeywell's Solstice® N40 = R448A [PDF] Honeywell Advanced Materials 115 Tabor Road Morris Plains, NJ 07950 honeywell-refrigerants.com retrieved 2020/02/10 original source: https://www.fluorineproducts-honeywell.com/refrigerants/wp-content/uploads/2018/02/SPM-FLP-00643-PT-Chart-Solstice-N40_3x5_LR.pdf
7. R449A / XP40 Data, FSW Cannock Delta House,Fairway, Bridgtown, Cannock, Staffordshire, WS11 0DJ Email Sales@fsw.uk.com Tel: 01543 437 010 retrieved 2020/02/10 original source: https://www.fsw.uk.com/sites/www.fsw.uk.com/files/r449a-xp40-pt-chart.pdf
8. R452 Data, FSW, Op. Cit., retrieved 2020/02/10 original source: https://www.fsw.uk.com/sites/www.fsw.uk.com/files/r452a-xp44-pt-chart_0.pdf
9. R600A Data, Iso-Butane, A-Gas, op. cit. retrieved 2020/02/10 original source: https://www.agas.com/media/2423/r600a-iso-butane-pt-chart.pdf
10. R600A Data, Iso-Butane, A-Gas, op. cit. retrieved 2020/02/10 original source: https://www.agas.com/media/6742/r1234yf-pt-chart-2.pdf
11. R507 Data, Agas, Op. Cit., https://www.agas.com/media/2421/r507-pt-chart.pdf
    
12. R502 Datra, R502 is replaced by R402A / R-408A, retrieved 2020/02/10 original source: http://www.pchetz.com/_Uploads/dbsAttachedFiles/R502PressureEnthalpy.pdf
13. R402A Data, REFRIGERANT CHANGEOVER GUIDELINES R-502 TO R-402A/R-408A [PDF] (2005) Copeland / Emerson Climate Technologies, 1675 W. Campbell Road Sidney, OH 45365-0669 (937) 498-3011 copeland-corp.com
    
    Excerpts: Copeland does not advocate the wholesale changeover of CFC refrigerants to HCFCs or HFCs. If a system is not leaking refrigerant to the atmosphere, and is operating properly, there is no technical reason to replace the CFC refrigerant.
    
    In fact, changing the refrigerant may void the U.L. listing of the unit. However, once the decision has been made to make the change from R-502 to the interim R-402A or R-408A, the following guidelines are recommended.
    
    R-402A/R-408A should be used only in systems that currently use R-502. It should not be mixed with R-502 or any other refrigerant nor should it be used to replace CFC-12 or HCFC-22
14. R408A Data, see #13 above.
15. Daikin, R407H PROPERTIES, USE & HANDLING [PDF] Daikin Chemical Europe GmbH Am Wehrhahn 50 40211 Düsseldorf, Germany Phone: +49 211-179225-0 Fax: +49 211-179225-39 daikinchem.de
    Excerpt:
    R407H can be used as a Drop-In refrigerant in R404A / R507 systems. A Drop-In is the easiest way to convert a refrigeration system to another refrigerant. It is linked with minor changes and it usually uses the same oil type.
16. Eco Freeze, E.F. International bvba Boombekelaan 11E B-2660 Hoboken (Antwerp) Belgium + 32 498 648 933 – Arya Mohadjerin arya@eco-freeze.com source of our Eco-32 pressure chart given in the table above, retrieved 2021/12/22 original source: https://eco-freeze.com/resources/#32chart
17. Engineering Toolbox, "Refrigerants - Environmental Properties, Refrigerants - Ozone Depletion (ODP) and Global Warming Potential (GWP)", retrieved 2021/12/22 original source: https://www.engineeringtoolbox.com/Refrigerants-Environment-Properties-d_1220.html
    This article provided data for some of the gas properties entered in the table above.
18. The GWP of R32 was increased from 675 to 771 in August, 2021 by the Intergovernmental Panel on Climate Change (IPCC), sixth assessment report “Climate Change 2021 – The Physical Science Basis.”
19. US EPA UNACCEPTABLE SUBSTITUTE REFRIGERANTS [PDF] U.S. EPA, retrieved 2021/12/22 original source: https://www.epa.gov/snap/unacceptable-substitute-refrigerants
20. R134 REFRIGERANT PRESSURE / TEMPERATURE CHARTS - separate article
21. R22 REFRIGERANT PRESSURE / TEMPERATURE CHARTS - and rules of thumb - separate article
22. R32 REFRIGERANT PRESSURE / TEMPERATURE CHARTS - separate article
23. R410A REFRIGERANT PRESSURE / TEMPERATURE CHARTS - separate article

Comparison of Ambient Pressure/Temperature for Refrigerants

Notes to the table above

• These are vapour pressures unless stated otherwise
• [6] Alternative Chart for R448A (N40) Pressure & Temperature, FSW op. cit. retrieved 2020/02/10 original source: https://www.fsw.uk.com/sites/www.fsw.uk.com/files/r448a-n40-pt-chart.pdf

Refrigerant Pressure / Temperature Chart & Table Downloads

• R22 REFRIGERANT PRESSURE / TEMPERATURE CHARTS [Web Article] Troubleshooting, repairing, + R22 chart downloads.
• REFRIGERANT PRESSURE / TEMPERATURE CHARTS for R-22, R-410A, R-134A, R-404A REFRIGERANTS [PDF] Advantage Engineering, Inc. 525 East Stop 18 Road Greenwood, IN 46142USA, Tel: 317-887-0729 Web site: www.AdvantageEngineering.com Email: sales@AdvantageEngineering.com
  
  HCFC-142b REFRIGERANT GAS Product Information [PDF] Op. Cit.,
• R32 REFRIGERANT PRESSURES [Web Article] includes downloadable PDFs of R-32 pressure/temperature charts
• R32 PRESSURE / TEMPERATURE CHART [PDF] Agas, Op. Cit., retrieved 2020/02/10 original source: https://www.agas.com/media/2427/r32-pt-chart.pdf
• R134 REFRIGERANT PRESSURE / TEMPERATURE CHARTS [Web Article] + additional data on & downloads for R-134
• HFC R-134A PRESSURE TEMPERATURE CHART [PDF], Pacific Sea Breeze Marine Products, 100 Grace Way, Scotts Valley, CA 95066 USA, Tel: 831-600-7878 Website: http://pacificseabreeze.com/technical_library
• R134A REFRIGERANT PT CHART [PDF] Agas, Op, Cit. retrieved 2020/02/10 original source: agas.com/media/2404/r134a-pt-chart.pdf
• R410A REFRIGERANT PRESSURE / TEMPERATURE CHARTS [Web Article] Troubleshooting, repairing, + R-410a refrigerant pressure chart downloads.
  
• REFRIGERANT TEMPERATURE / PRESSURE CHARTS for R-407, R-22, R410a, R-407c, R-134a, R404a, [PDF], Op. Cit.,
• REFRIGERANT PRESSURE / TEMPERATURE CHARTS for R-11, R-113, R-123, R-12, R-13, R-134A, R-114, R-14 or Freon-14, Tetrafluoromethane,R-22, R-23, R-410A, R-409A, R-416A, R-500, R-503, R-507, R-503 [PDF]
  
  Airgas Refrigerants, Inc., Headquarter Office 2530 Sever Road, Suite 300 Lawrenceville, GA 30043 Tel: 1-800-473-3766, Website: www.airgasrefrigerants.com Email: ARF-Contact.us@airgas.com
• HCFC-142b REFRIGERANT GAS Product Information [PDF], DAIKIN AMERICA, INC. 20 Olympic Drive, Orangeburg, NY 10962, USA Phone: +1-845-365-9500 Toll-Free: +1-800-365-9570 Facsimile: +1-845-365-9598 http://www.daikin-america.com,
  
  DAIKIN CHEMICAL EUROPE GmbH Immermannstr. 65D, 40210 Dusseldorf, Germany Phone: +49-211-179225-0 Facsimile: +49-211-1640732 http://www.daikinchem.de
  
  Chemicals Division Umeda Center Bldg., 2-4-12, Nakazaki-Nishi, Kita-ku, Osaka 530-8323, Japan Phone: +81-6-6373-4342 Facsimile: +81-6-6373-4390 http://www.daikin.com/chm
• HCFC R-142b REFRIGERANT GAS MSDS [PDF], National Refrigerants, Inc., 661 Kenyon Ave., Bridgeton NJ 08302, USA

Overview of Refrigerant Types - past and current

The types of refrigerants can be a confusing soup of acronyms. Here's a summary of the different types of refrigerants:

• CFCs are ChloroFluoroCarbons - first generation refrigerants like R12 (early replacements for still earlier & harder-to-use CO₂ refrigerant) & R22 (1950s & later) widely used in refrigerators and air conditioners.
  
  R12 was phased out in the US in 1994. R22 was phased out in 2010 and are no longer widely available.
• HCFCs = HydroChloroFluoroCarbon - refrigerants that were considered less damaging to the environment than CFCs. Less harmful to the ozone layer.
  
  HCFCs and CFCs both contain chlorine that was found to damage the earth's ozone layer. The Montreal Protocol was an agreement to phase out both CFCs & HCFCs.
• HFCs = HydroFluoroCarbons - a 3rd generation of refrigerants less damaging to the ozone layer were intended to replace older refrigerants.
  
  Current HFCs were considered less damaging to the environment than CFCs and HCFCs.
  
  HFCs are made up of hydrogen, fluorine, and carbon. They are now recognized as a serious contributor to greenhouse gases and global warming.

In sum there were at least two classes of damage:

Holes in the ozone layer:

Chlorine-containing refrigerants that contributed to the ozone hole (consider getting skin cancer in Australia). These include CFCs and HCFCs.

Greenhouse gases:

Greenhouse gas formation that contributes to global warming. These include HCFCs and HFCs.

Environmental Alternatives

The EU has proposed more climate-friendly alternatives to HFCs. The article below provides a more-extensive list of alternatives to HFC type refrigerants.

• CLIMATE FRIENDLY ALTERNATIVES to HFC REFRIGERANTS - EU [PDF] European Commission for Climate Action, (This department leads the European Commission's efforts to fight climate change at EU and international level.)
  European Commission, Charlemagne building, Rue de la Loi 170, 1040 Brussels Belgium (Visitors Centre), Web: https://ec.europa.eu/info/index_en - retrieved 2021/12/22, original source: https://ec.europa.eu/clima/eu-action/fluorinated-greenhouse-gases/climate-friendly-alternatives-hfcs_en).

In choosing refrigerants that reduce or eliminate the contribution of those products to global warming, alternatives include:

• Natural refrigerants
• HFCs with lower GWP, such as R32
• Hydrofluoroolefins (HFOs)
• HFC-HFO blends

More about environmental concerns updates about refrigerants are given just below.

Refrigerant Type & Environmental Concerns Update

Illustration, excerpted from TRANSITIONING TO LOW-GWP ALTERNATIVES in Residential & Light Commercial Air Conditioning [PDF] (live link given just below), U.S. EPA, accounts for an estimated 36.7 metric tons of CO₂ equivalent released into the atmosphere by residential and light commercial A/C equipment in 2014.

At COMPARISON of REFRIGERANT GAS PROPERTIES we explained the two most widely-used measures of environmental impact of refrigerant gases, GWP and ODP, and that table makes clear that there are significant differences in both Global Warming Potential and Ozone Depletion Potential among refrigerants.

More about environmental concerns among refrigerants and the move towards refrigerants that offer less contribution to global warming and its costs is in the following articles:

• CLIMATE FRIENDLY ALTERNATIVES to HFC REFRIGERANTS - EU [PDF] European Commission for Climate Action, (This department leads the European Commission's efforts to fight climate change at EU and international level.)
  European Commission, Charlemagne building, Rue de la Loi 170, 1040 Brussels Belgium (Visitors Centre), Web: https://ec.europa.eu/info/index_en - retrieved 2021/12/22, original source: https://ec.europa.eu/clima/eu-action/fluorinated-greenhouse-gases/climate-friendly-alternatives-hfcs_en).
• TRANSITIONING TO LOW-GWP ALTERNATIVES in Residential & Light Commercial Air Conditioning [PDF] (2015) US Environmental Protection Agency (EPA), SNAP (Significant New Alternatives Policy), Contact: https://www.epa.gov/aboutepa/forms/contact-epa, Web: www.epa.gov, retrieved 2021/12/22, original source: https://www.epa.gov/sites/default/files/2015-09/documents/epa_hfc_residential_light_commercial_ac.pdf
  
• TRANSITIONING TO LOW-GWP ALTERNATIVES in Domestic Refrigeration [PDF] (2016) U.S. EPA (SNAP, retrieved 2021/12/22, original source: https://www.epa.gov/sites/default/files/2016-12/documents/transitioning_to_low-gwp_alternatives_in_domestic_refrigeration.pdf
• TRANSITIONING TO LOW-GWP ALTERNATIVES in Commercial Refrigeration [PDF] (2016) U.S. EPA, (SNAP), retrieved 2021/12/22, original source: https://www.epa.gov/sites/default/files/2016-12/documents/transitioning_to_low-gwp_alternatives_in_commercial_refrigeration.pdf
• TRANSITIONING TO LOW-GWP ALTERNATIVES in Passenger Vehicle Air Conditioners [PDF] (2015) U.S. EPA, (SNAP), retrieved 2021/12/22, original source: https://www.epa.gov/sites/default/files/2015-09/documents/epa_hfc_passenger_vehicle_ac.pdf
• K-J Thomas Mechanical, "HFC Refrigerants and Climate Change" [web article], K-J Thomas Mechanical, 6175 Trevarton Dr. Longmont, CO 80503 USA [Not Open to Walk-in Traffic] Tel: 303-435-8141 - retrieved 021/12/21 original source: https://www.kjtmechanical.com/webapp/p/574/hfc-refrigerants-and-climate-change
  Excerpts:
  
  ... the Paris Climate Accord, reached in December 2015 “gentleman’s agreement” [goal] is to reduce greenhouse gas emissions to 0 by 2050 and hold the increase in global temperature to 1.5 degrees Celsius.
  ...
  President Obama pledged that the United States would reduce greenhouse gas emissions approximately 25 percent by 2025 using multiple means including ... reducing HFC refrigerants use ...
  
  In June 2017, President Trump withdrew the United States from the agreement.
  
  However, as of July 2017, 350 [U.S.] mayors have formed the Climate Mayors and pledged to continue to follow or increase the Paris guidelines. In fact, many of them have committed to the goal of 100% clean energy.
  ...
  The Kigali Amendment on October 15, 2016 to the Montreal Protocol specifically addresses HFC refrigerants, and stipulates a timeline for limiting production and use. Rich developed countries in the European Union and the US will begin with a 10% reduction (from 2012 baseline) in the use and production of HFCs in 2019 down to by 85% by 2036. Developing countries have a more lenient timeline.
  
  Reduction will avoid up to .5 degree Celsius of warming by the end of the century.
  
  Note that the US has not ratified the Kigali treaty yet (and it’s fate would be uncertain under the new administration), but indications are that movement will continue in the direction of implementing the phasedown, whether legally required or not.