InspectApedia Diagnose & Fix What's Wrong at Your Building (2024)

  • POST a QUESTION or COMMENT about refrigerant pressure readings in air conditioners, heat pumps, & other refrigeration equipment

R-401a refrigerant pressure/temperature charts & guide to charge quantity for air conditioners & heat pumps.

This air conditioning repair article series discusses the the diagnosis and correction of abnormal air conditioner refrigerant line pressures as a means for evaluating the condition of the air conditioner compressor motor, which in turn, is a step in how we evaluate and correct lost or reduced air conditioner cooling capacity.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Editor/Publisher - See WHO ARE WE?

Typical R-410A Refrigerant Pressure / Temperatures

For every refrigerant type you use, you'll want to pick up a Refrigerant Pressure/Temperature chart from your supplier.

A typical R-410A refrigerant pressure/temperature chart will give refrigerant pressures at various (ambient) temperatures ranging from below freezing to over 160 °F.

Following the R410A pressure examples in our table you'll find free PDF downloads of detailed R410 refrigerant pressure charts.

Example R-410A Refrigerant Temperature vs Pressure Data

Ambient Temperature in °F1R410A Vapor Pressure at Sea LevelTemperature (°C) R-410A Low Side Pressure2R-410A High Side Pressure3
-10°F26.9 psi-23.3
0°F48.4 -17.8
40°F11983 psig257 psig
45°F 120130418
75°F218.723.9120 psig410-420 psig

Notes to the table above

  • Typical Low Side Pressure Range for R410A in the field: 115-120 psi
  • Typical High Side Pressure Range for R410A in the field: 410-420 psi
  • By 2025, high Global Warming Potential (GWP) refrigerants with a GWP of over 750, will be banned together with the systems using that gas.
  • R410A has a GWP > 2,000.
  • Measuring the refrigerant pressure in air conditioning, heat pump or other refrigerant systems can diagnose a range of operating problems including a refrigerant leak, over charging or under charging.

    Refrigerant pressure readings measured at the air conditioning compressor/condenser unit and which are found to be too low on the high pressure side (compressor output) or on the low pressure side (compressor input or suction line) can indicate a problem with the compressor's ability to develop normal operating pressure ranges and thus will affect the cooling capacity of the air conditioning system.

R410A Refrigerant Rules of Thumb

On a properly-charged and working air conditioning system using R-410A refrigerant

  • R-410A Low-Side Typical Operating Pressure-Range = 102-145 psig (varying by indoor wet bulb temperature and outdoor ambient temperature, where higher heat loads increase the vapor line pressure)

Other Properties for R410A Refrigerant

  • R410A temperature/pressure relationship: see the table above
  • R410A alternative names: 50%CH2F2 / 50%CHF2CF3 - 410A is a mixture of difluoromethane (CH2F2, R-32) and pentafluoroethane (C2HF5, R-125)
  • R410A boiling point: -55.3°F or -48.5°C at atmospheric pressure (sea level or 1 ATM)
  • R410A critical temperature 72.8°C
  • R410A density: 3.0 g/cm3, in gas form - as a colorless gas, Vapour density: 3.0, Vapor pressure at 21.1°C (MPa) = 1.383
  • R410A molar mass: 86.47 g/mol
  • R410A vapor pressure at 21.1°C (MPa) = 1.383
  • R410A gas cylinder identification: rose color
  • R410A status: in use

1. Outdoor ambient temperature

2. Typical low pressure or suction side pressure for R410A is about 120 psi, varying by ambient temperature, here assuming 75°F, may vary by equipment and metering controls

3. Typical high side pressure for R410A is < 600 psi at an ambient outdoor temperature of 95 °F, may vary by equipment

4. These psig readings for R-410A are what you'd expect the pressure of the gas to be in an enclosed container at the temperature given and at steady state.

These pressures are not suction or low-side nor compressor output or high-side pressures as those depend on the compressor model and the refrigerant metering device. This operating pressure for R-410A example was given by ACHR News in 2002:

... to produce an evaporating temperature of 40 degrees F and a condensing temperature of 115 degrees, the suction and head pressures would be 83 psia and 257 psia in an R-22 system, while they would be 133 and 406 psia, respectively, in an R-410A system. - Checket-Hanks, Barbara A., "Guidelines for Troubleshooting R-410A Systems", ACHR News 16 May 2002, retrieved 2016/08/29 original source:

An air conditioner or heat pump using R-410A refrigerant may operate at pressures exceeding 600 psi. A typical Carrier HVACR unit incorporates a high-pressure safety switch that operates at 610 psi and a low pressure (loss of refrigerant detection safety device) that operates at about 20 psi.

Low pressure refrigerant switches on Carrier HVACR typically open at 50 psi and close at 100 psi.

- Prah, Frank, CMS, "Refrigerant 410A", [PDF] Refrigeration Service Engineers Society, 1666 Rand Road, Des Plaines IL 60016 USA, Tel: 847-297-6464, retrieved 2016/08/29, original source:

R-410A Refrigerant Pressure / Temperature Chart Downloads

Both older R-22 and R-134 operate at lower pressures than R-410A.

  • BPA, R-410A PRESSURE TEMPERATURE CHART [PDF] - original source: Bonneville Power Authority, website: retrieved 2019/02/11 original source: (dead link in 2024 - Ed)

    data generated using the NIST REFPROP Database (Lemmon, E.W., Huber, M.L., McLinden, M.O. NIST Standard Reference Database 23: Reference Fluid Thermodynamic and TransportProperties-REFPROP, Version 9.0, National Institute of Standards and Technology, Standard Reference Data Program, Gaithersburg, (2010) retrieved 2019/02/11 from this additional source:

  • Prah, Frank, REFRIGERANT 410A INFORMATION [PDF] Refrigeration Service Engineers Society, 1666 Rand Road, Des Plains IL 60016, (2001) retrieved 2017/09/20, original source:
  • National Refrigerants, THERMODYNAMIC PROPERTIES of R410A [PDF], (2010) National Refrigerants Inc., Website:, retrieved 2019/02/11 original source:
  • Advantage Engineering, 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: Email:
  • 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]

Watch out: Excerpts from Carrier’s Puron® Quick Reference Guide

“When charging 410A (liquid refrigerant only), use a commercial-type metering device in the manifold hose when charging into the suction line with the compressor operating.”

“Manifold sets should be a minimum 700 psig on the high side and minimum 180 psig low side, with 550-psig low-sided retard. Use hoses with a minimum 700-psig service pressure rating.”

“Be sure that servicing equipment and replacement components are designed to operate with [410A].” The recovery cylinder service pressure rating must be 400 psig, DOT 4BA400, or DOT 4BW400.

R410A Evaporating & Condensing Temperatures

Example R410A Evaporating & Condensing Temperatures & Suction & Head Pressures vs bulb temperatures

Evaporator Temp °FCondenser Temp °F Suction Pressure psiaHead Pressure psiaIndoor Temp °F
Dry Bulb
Outdoor Temp °F
Dry/Wet Bulb
86 29960°F 30/28°F 4
10332960°F40/38°F 4
12437960°F50/47°F 4
45°F 120°F1304183
14643060°F60/57°F 4
14546170°F60/57°F 4
14449080°F60/57°F 4

Notes to the table above

  1. To charge correctly, use the subcooling method
  2. Typical pressure range at 75F: suction side 100-120 psi
  3. HVAC Education Australia, The ESSENTIALS of WORKING WITH R-410A [PDF] [no contact information given except website as cited below] retrieved 2019/02/11 original source:
  4. R410A HEAT PUMP HEATING CHECK CHART PAYNE PH16NA [PDF] for 16 SEER 2-Stage Split System Heat Pump using R410A, 2-5 Tons, (2012) Payne Heating & Cooling Systems, 7310 W. Morris St. D Indianapolis, IN 46231 USA, retrieved 2019/02/11
  5. Suction side: add 25°F to outside air temperature and use the refrigerant chart to convert to psig
  6. ACHR News, "Guidelines For Troubleshooting R-410A Systems" ACHR News, Main Office 2401 W. Big Beaver Rd., Suite 700 Troy, MI 48084 Phone: 248-362-3700 retrieved 2019/02/11 original source:<

Correcting R-410a Refrigerant Pressure & Leaks

Refrigerant Pressures & Pressure Diagnosis

  • - home,
    • TYPICAL REFRIGERANT PRESSURES found in air conditioners, heat pumps, refrigeration equipment for various refrigerant gases
    • COMPARISON of REFRIGERANT GAS PROPERTIES - table just below gives replacements for now-obsolete refrigerants like R22
    • COMPARISON of REFIGERANT GAS PRESSURES/TEMPERATURES - refrigerant pressure of various gases at the same temperature?

Refrigerant Pressure & Leak Correction

If you already know your refrigerant pressures are wrong or that you have a refrigerant leak, please see



Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see

Are Refrigerant Pressures the same for a heat pump as for an air conditioner?

when installing 410a is the pressure gauge around 40
the same on a heat pump as it is on a regular air conditioner - On 2020-04-09 by carl

Reply by (mod) - Yes

Yes, Carl, and thanks for asking.

"Around 40" - are you referring to ambient temperature, refrigerant line temperature or something else?

Typically on a heat pump on the suction line the saturation temperature will be set to about 20 to 25 degrees F below the outdoor ambient temperature.

The refrigerant doesn't know if it's being used in heating mode or cooling mode; the temperature/pressure charts for R410A as well as for other refrigerants only present pressure and temperature ranges.

Approximate R410a or R43a pressure at the condenser when it's off

On a split system air conditioner, what should the approximate pressures be at condensing unit using 410A or 32A when the unit is off?
And what should the pressure be when the unit is operating? - On 2020-02-10 by Dave Wane Plumbing -

Reply by (mod) -

Dave, take a look in the refrigerant pressure tables given in the article on this page - for R410A for example.

When the A/C system is OFF and has been off long enough for pressures to equalise across the thermostatic expansion valve, both high-side and low-side pressures will be the same.

The measured pressure of the refrigerant, when the compressor has been off for a time and the HI and LO sides are equalized, is simply a function of the ambient pressure and of course your elevation above sea level.

For example, R410A, at an ambient temperature of 60°F will have a pressure of 170.7 psi.

When the unit is operating the head pressure goes up and the suction side pressure goes down. We describe operating pressures in tables and in notes to the tables given here.

For example,
Typical low pressure or suction side pressure for R410A is about 120 psi, varying by ambient temperature, here assuming 75°F, may vary by equipment and metering controls

Typical high side pressure for R410A is < 600 psi at an ambient outdoor temperature of 95 °f, may vary by equipment

thank you for asking.

Question: will older refrigerant gauge set work with R410?

2019/08/10 Karl Seyer

I have an AC compressor using R410, can I use an older gauge, or is the pressure too high for the the old Refrigerants, like R12 & R35?

Reply by Mod

The pressure range will be within your older gauge set and in fact you should see an R-410a scale on the gauge face of some equipment.


Continue reading at - home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

  • - home
  • - home
  • - home

Suggested citation for this web page

R410A REFRIGERANT PRESSURE / TEMPERATURE CHARTS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification
when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions

Comment Form is loading comments...

Citations & References

In addition to any citations in the article above, a full list is available on request.

  • In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested


  • Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

    Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The HOME REFERENCE BOOK- the Encyclopedia of Homes and to use illustrations from The ILLUSTRATED HOME .

    Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.


InspectApedia Diagnose & Fix What's Wrong at Your Building (2024)


Top Articles
Latest Posts
Article information

Author: Stevie Stamm

Last Updated:

Views: 6076

Rating: 5 / 5 (80 voted)

Reviews: 95% of readers found this page helpful

Author information

Name: Stevie Stamm

Birthday: 1996-06-22

Address: Apt. 419 4200 Sipes Estate, East Delmerview, WY 05617

Phone: +342332224300

Job: Future Advertising Analyst

Hobby: Leather crafting, Puzzles, Leather crafting, scrapbook, Urban exploration, Cabaret, Skateboarding

Introduction: My name is Stevie Stamm, I am a colorful, sparkling, splendid, vast, open, hilarious, tender person who loves writing and wants to share my knowledge and understanding with you.