What Pressure Should R-449A Be?
Updated October 20, 2026
R-449A A1 Lower toxicity, no flame propagation
You are on an R-449A system — an R-404A replacement used in retrofits and new racks, sold as Chemours Opteon XP40 — with gauges connected and suction that looks low if you still have R-404A numbers in your head.
Compare R-449A suction to R-404A memory and you will over-add refrigerant on a box that was fine; on a rack full of product that is an expensive way to learn the fluid reads lower. (R-449A is not R-448A — Opteon XP40 is R-449A.)
This page gives R-449A suction by application at the AHRI walk-in coil temperatures, head pressure by outdoor temperature, and a direct comparison with R-404A on the same box.
R-449A suction is about 8.1–11.6 psig at a −20°F freezer coil and 47–54 psig at a 25°F cooler coil, with head around 258–338 psig at 95°F outdoors. On a retrofitted R-404A box it reads noticeably lower suction than R-404A, so compare to R-449A numbers, not to R-404A memory.
R-449A suction pressure by application
Suction is set by the evaporator coil temperature. The AHRI 1250-2020 walk-in rating points — a 25°F cooler coil and a −20°F freezer coil — give the two suction bands you check most. Read suction on the dew curve; R-449A has real glide.
| Application | Suction (psig / kPa) |
|---|---|
| Walk-in cooler (25°F coil) | 47–54 psig 322–374 kPa |
| Walk-in freezer (−20°F coil) | 8.1–11.6 psig 56–80 kPa |
Head pressure by outdoor temperature
Head is set by the condenser and climbs with the outdoor air, the same on a cooler or a freezer. Find your outdoor temperature down the left column.
| Outdoor | Head (psig / kPa) |
|---|---|
| 65°F 18.3°C | 164–223 psig 1,130–1,539 kPa |
| 70°F 21.1°C | 178–240 psig 1,224–1,655 kPa |
| 75°F 23.9°C | 192–258 psig 1,324–1,777 kPa |
| 80°F 26.7°C | 207–276 psig 1,428–1,905 kPa |
| 85°F 29.4°C | 223–296 psig 1,539–2,040 kPa |
| 90°F 32.2°C | 240–316 psig 1,655–2,181 kPa |
| 95°F 35.0°C | 258–338 psig 1,777–2,328 kPa |
| 100°F 37.8°C | 276–360 psig 1,905–2,483 kPa |
| 105°F 40.6°C | 296–384 psig 2,040–2,645 kPa |
| 110°F 43.3°C | 316–408 psig 2,181–2,814 kPa |
| 115°F 46.1°C | 338–434 psig 2,328–2,991 kPa |
R-449A vs R-404A on the same box: glide and dew-point reading
On the same 25°F cooler coil, R-449A reads about 19% lower on suction versus R-404A and about 1% higher on the head — lower suction is normal, not an undercharge. R-449A also has real glide, so read suction on the dew curve and the liquid line on the bubble curve; using R-404A's near-azeotropic habits here misreads superheat by the glide.
| Refrigerant | Low side (psig / kPa) | High side (psig / kPa) |
|---|---|---|
| R-449A | 47–54 psig 322–374 kPa | 258–338 psig 1,777–2,328 kPa |
| R-404A | 58–66 psig 400–458 kPa | 254–333 psig 1,753–2,298 kPa |
R-449A readings that point to a problem
These are refrigeration faults; match a suspect reading to the pattern below, reading suction on the dew curve, then confirm with a calculator before adding refrigerant.
A healthy R-449A system at 95°F outdoors reads about 47–54 psig suction on a 25°F cooler coil, 8.1–11.6 psig on a −20°F freezer coil, and 258–338 psig head.
| Fault | Suction | Head | Superheat | Subcooling | First thing to check |
|---|---|---|---|---|---|
| Likely undercharge | low | low | high | low | Find and fix the leak, then recharge by weight |
| Likely overcharge | high | high | low | high | Verify condenser airflow, then recover to target |
| Likely restriction | low | normal–low | high | high | Look for a temperature drop across the filter-drier or liquid line, then check the metering device. |
| Likely metering device overfeeding | high | low | low | low | A TXV or EEV stuck open or with a loose sensing bulb; on a fixed-orifice system, the piston size. |
Confirm a reading before adjusting the charge: the pressure diagnostic tool, low suction pressure and high head pressure guides walk a reading to its cause.
Frequently asked questions
What should R-449A suction pressure be?
About 8.1–11.6 psig at a −20°F freezer coil and 47–54 psig at a 25°F cooler coil, read on the dew curve. Suction is set by the box temperature, not the weather, so pair the reading with the application before judging it. On a retrofit it will sit below the old R-404A numbers.
What is normal R-449A head pressure?
About 258–338 psig at 95°F outdoors, rising on hotter days because the condensing temperature sits above the outdoor air. Head is set by the condenser and ambient, not the box, so it is the same on a cooler or a freezer. Read the head chart above for your outdoor temperature.
Why does R-449A read lower suction than R-404A on the same box?
Because R-449A's saturation pressure is lower — about 19% lower at the cooler coil condition. On a retrofitted box that lower suction is expected and not an undercharge. Compare to the R-449A numbers above, and read superheat on the dew curve because R-449A glides where R-404A barely does.
How these numbers are calculated
Every pressure here is R-449A's saturation pressure at the stated temperature, calculated with CoolProp 7.2.0. Suction (low side) uses the saturated-vapor (dew) pressure; head (high side) uses the saturated-liquid (bubble) pressure.
Suction uses the AHRI 1250-2020 walk-in coil temperatures — 25°F for a cooler, −20°F for a freezer — read on the dew curve at the coil ±3°F; head is a condenser running 10–30°F above the outdoor air. We use 95°F as the reference because it is one of the AHRI 1250 outdoor rating temperatures for condensing units.
Sources: CoolProp 7.2.0; AHRI 1250-2020 (walk-in ratings). Your equipment maker's charging chart or the unit data plate overrides these reference values for that specific system.