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.
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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 |
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Ambient Temperature in °F1 | R410A Vapor Pressure at Sea Level | Temperature (°C) | R-410A Low Side Pressure2 | R-410A High Side Pressure3 |
-10°F | 26.9 psi | -23.3 | ||
0°F | 48.4 | -17.8 | ||
10°F | 62 | |||
32°F | 101.4 | 0 | ||
40°F | 119 | 83 psig | 257 psig | |
45°F | 120 | 130 | 418 | |
51°F | 145 | |||
55°F | 155 | |||
60°F | 170.7 | 15.6 | ||
62°F | 175 | |||
64°F | 180 | |||
66°F | 185 | |||
70°F | 201 | |||
72°F | 205 | |||
73°F | 210 | |||
75°F | 218.7 | 23.9 | 120 psig | 410-420 psig |
76°F | 220 | |||
80°F | 236.5 | 26.7 | ||
82°F | 240 | |||
84°F | 250 | |||
85°F | 254 | |||
87°F | 260 | |||
90°F | 275 | |||
93°F | 290 | |||
95°F | 296.4 | 35 | ||
97°F | 305 | |||
100°F | 318.6 | 37.8 | ||
109°F | 365 | |||
110°F | 366 | |||
118°F | 405 | |||
134°F | 500 | |||
150°F | 613.9 | 65.6 |
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.
On a properly-charged and working air conditioning system using R-410A refrigerant
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: http://www.achrnews.com/articles/87788-guidelines-for-troubleshooting-r-410a-systems
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: https://www.rses.org/assets/r410a/R-410A.PDF
Both older R-22 and R-134 operate at lower pressures than R-410A.
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.
Example R410A Evaporating & Condensing Temperatures & Suction & Head Pressures vs bulb temperatures |
|||||
Evaporator Temp °F | Condenser Temp °F | Suction Pressure psia | Head Pressure psia | Indoor Temp °F Dry Bulb |
Outdoor Temp °F Dry/Wet Bulb |
40°F | 115°F | 83 | 257 | ||
86 | 299 | 60°F | 30/28°F 4 | ||
103 | 329 | 60°F | 40/38°F 4 | ||
124 | 379 | 60°F | 50/47°F 4 | ||
45°F | 120°F | 130 | 418 | 3 | |
146 | 430 | 60°F | 60/57°F 4 | ||
145 | 461 | 70°F | 60/57°F 4 | ||
144 | 490 | 80°F | 60/57°F 4 |
If you already know your refrigerant pressures are wrong or that you have a refrigerant leak, please see
...
Below you will find questions and answers previously posted on this page at its page bottom reader comment box.
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.
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.
...
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