R-410A (Puron)
R-410A Superheat & Subcooling Calculator
Check charge on R-410A systems, still the biggest installed base in the field. The calculator opens preloaded for R-410A with a full PT chart, TXV and fixed orifice targets, and the four-quadrant diagnostic that turns two readings into a diagnosis.
R-410A Pressure-Temperature Chart
| Pressure (psig) | Sat. Temp (°F) |
|---|---|
| 26.9 | -20°F |
| 36.8 | -10°F |
| 48.6 | 0°F |
| 55.2 | 5°F |
| 62.3 | 10°F |
| 70 | 15°F |
| 78.3 | 20°F |
| 87.3 | 25°F |
| 96.8 | 30°F |
| 107 | 35°F |
| 118 | 40°F |
| 130 | 45°F |
| 142 | 50°F |
| 155 | 55°F |
| 170 | 60°F |
| 185 | 65°F |
| 201 | 70°F |
| 217 | 75°F |
| 235 | 80°F |
| 254 | 85°F |
| 274 | 90°F |
| 295 | 95°F |
| 317 | 100°F |
| 340 | 105°F |
| 365 | 110°F |
| 391 | 115°F |
| 418 | 120°F |
| 446 | 125°F |
| 476 | 130°F |
The two anchor points worth memorizing: 118 psig is a 40°F evaporator, and 317 psig is a 100°F condenser. Everything else on a residential cooling call is a short interpolation from one of those.
R-410A Target Superheat & Subcooling
| Metering device | Target superheat | Target subcooling | Charging method |
|---|---|---|---|
| TXV | 8–15°F | 8–14°F | Charge by subcooling; the TXV holds superheat |
| Fixed orifice (piston) | 5–20°F | 4–10°F | Charge by superheat from the manufacturer charging chart |
R-410A: The Installed Base You Service Every Day
R-410A carried residential air conditioning from roughly 2010 to 2025. After R-22 equipment ended in 2010, virtually every ducted split system, package unit, and heat pump installed in the US shipped on R-410A, which means tens of millions of systems in the 10-to-15-year-old range that you will be diagnosing and recharging for another decade. It is a near-azeotropic blend of R-32 and R-125 (50/50 by weight) running on POE oil, with a GWP of 2,088, which is why the AIM Act phasedown pushed new equipment to R-454B and R-32 starting with January 2025 manufacture.
Phasedown changes the economics of a service call more than the technique. HFC production allowances step down on a schedule, so R-410A per-pound cost keeps rising. That makes "find the leak" the professional answer where "add a couple pounds" used to slide by, and it makes accurate charge verification worth the extra ten minutes: overcharging a system now wastes real money on both sides of the invoice.
R-410A Charging Notes
Charge R-410A as liquid from the cylinder, throttled slowly into the suction side. As a blend it should always be liquid-charged, even though its near-zero glide means fractionation is a technicality rather than a field problem. On TXV systems, charge to subcooling: get the system stable at steady-state, verify airflow first (a matted filter fakes a charge problem), then trim charge until subcooling lands on the nameplate value. On fixed-orifice systems, charge to the superheat chart using outdoor ambient and indoor wet bulb.
The most common R-410A misdiagnosis is charging by pressure alone. A 40°F evaporator at 118 psig is only meaningful once you know the suction line temperature; without it, low pressure could be low charge, low airflow, or a cold day. Superheat and subcooling turn raw pressures into a diagnosis, which is exactly what this calculator automates.
Worked Example: R-410A Split System with TXV
A 12-year-old R-410A split system, TXV metering, on a 90°F afternoon. Field readings: suction pressure 118 psig, suction line temperature 51°F, liquid pressure 317 psig, liquid line temperature 96°F.
Saturated suction temp at 118 psig = 40°F
Superheat = 51°F − 40°F = 11°F
Saturated liquid temp at 317 psig = 100°F
Subcooling = 100°F − 96°F = 4°F
Diagnosis: Superheat 11°F is inside the 8–15°F TXV target, but subcooling 4°F is below the 8–14°F target. Normal superheat with low subcooling on a TXV system means the valve is still compensating while the condenser runs short of liquid: the system is slightly low on charge. On a unit this age, leak-search the coils and service valves before adding refrigerant, then charge until subcooling reaches the nameplate target.
R-410A Charging FAQs
What is normal superheat for R-410A?
With a TXV, target superheat for R-410A is 8-15°F measured at the suction line near the outdoor unit. With a fixed orifice (piston), target superheat depends on outdoor ambient and indoor wet bulb, typically 5-20°F, so use the manufacturer charging chart. Below 5°F superheat, liquid floodback to the compressor becomes a real risk.
What is normal subcooling for R-410A?
Target subcooling for R-410A with a TXV is 8-14°F, and most equipment nameplates specify a value in that window (often 10-12°F). Subcooling is the primary charging indicator on TXV systems because the valve holds superheat steady while charge level shows up in the condenser. Low subcooling means low charge; high subcooling means overcharge or a restriction.
What pressures should R-410A run at?
On a typical cooling call, the evaporator runs around 40°F saturated, which is about 118 psig suction. The condenser runs roughly 15-25°F above outdoor ambient, so on a 95°F day condensing at 110-120°F puts liquid pressure around 365-418 psig. Pressures far outside those windows point to a charge, airflow, or component problem rather than a bad gauge.
Is R-410A discontinued? Can I still buy it?
R-410A is being phased down, not banned. New residential AC and heat pump equipment moved to A2L refrigerants (mostly R-454B and R-32) for units manufactured from January 1, 2025, but existing R-410A systems can be legally serviced indefinitely. Virgin and reclaimed R-410A remain available; prices are climbing as AIM Act production allowances step down, so leak repair matters more than it used to.
Can I top off an R-410A system with R-454B or R-32?
No. Mixing refrigerants contaminates the circuit, makes PT readings meaningless, and leaves refrigerant that no recovery processor will accept. R-410A equipment is also not listed for flammable A2L refrigerants. Top off R-410A systems with R-410A only, and if you do not know what is in a system, identify it before adding anything.
Why is my superheat high and subcooling low on R-410A?
High superheat with low subcooling is the classic low-charge signature: the evaporator is starved, so vapor superheats excessively, and the condenser lacks liquid, so subcooling collapses. On an R-410A system of any age, that charge went somewhere. Find and repair the leak before adding refrigerant, especially at current R-410A prices.
Does R-410A have temperature glide?
Effectively no. R-410A is a near-azeotropic 50/50 blend of R-32 and R-125 with less than 0.3°F of glide, so a single saturation temperature per pressure works for both superheat and subcooling. Liquid charging is still the standard practice for any blend, but fractionation on R-410A is negligible in the field.
Other Refrigerants & Related Tools
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All-Refrigerant Calculator
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A2L Charge Limit Calculator
Maximum A2L charge for a room, or minimum room area for a charge, per UL 60335-2-40 and ASHRAE 15.2. Covers R-454B, R-32, and 6 more refrigerants.
EPA Refrigerant Leak Rate Calculator
Topping off a 15+ lb system triggers a leak rate calculation under 40 CFR 84.106 as of January 1, 2026. Run the EPA math and check the thresholds.
BTU / HVAC Load Calculator
Size the system by climate zone, insulation, windows, and duct location with automatic tonnage recommendations.
Chronic charge complaints on the same unit? Check the sizing.
A short-cycling oversized system masquerades as a charge problem year after year. Run the load by climate zone, insulation, and windows and compare it to the nameplate tonnage.