R22 vs R407C: The Retrofit That Isn't Quite
Updated October 3, 2026
R-407C is a ternary HFC blend (23/25/52 R-32/R-125/R-134a) designed as an R-22 retrofit. Similar pressure envelope, similar capacity, A1 safety class — but requires POE oil instead of R-22's mineral oil, and has ~11°F temperature glide that affects TXV behavior and superheat measurement.
- GWP (100-yr)
- 1,774
- Lubricant
- POE
- Glide @ 0°C
- 11.0°F
PT curves, overlaid
Solid line = bubble, dashed = dew where the refrigerant has significant temperature glide.
Pressure comparison at service temperatures
Side-by-side pressure values at common service temperatures, computed from CoolProp 7.2.0. Useful for retrofit feasibility — pressure deltas within ±20% typically allow retrofit-compatible service equipment; larger deltas require component pressure-rating review.
| Temperature | R-22 | R-407C | Δ vs R-22 |
|---|---|---|---|
| −20°F | 10 PSIG | 14 PSIG | +34.6% |
| 0°F | 24 PSIG | 29 PSIG | +22.7% |
| 40°F | 69 PSIG | 80 PSIG | +17.0% |
| 70°F | 121 PSIG | 141 PSIG | +15.7% |
| 95°F | 182 PSIG | 209 PSIG | +15.2% |
| 120°F | 260 PSIG | 299 PSIG | +14.9% |
Pressure delta visualization: positive = R-407C runs higher than R-22; negative = lower. Service equipment pressure rating matters when delta exceeds ±20% on the discharge side. For R-22 (zeotropic blend) bubble pressure is shown; for R-407C same rule applies.
Property differences side by side
- GWP impact: R-22 = 1,810, R-407C = 1,774 (−2% vs R-22). GWP delta is modest.
- Lubricant: R-22: MO/AB; R-407C: POE. Retrofit requires oil change (mineral oil to POE).
- Glide change: R-22 glide = 0.0°F; R-407C glide = 11.0°F. Service measurement (superheat / subcooling) needs dew/bubble curve awareness for the higher-glide blend.
- AIM Act status: R-407C is affected by AIM Act phase-down; the other is not. Drives new-equipment specification decisions in US market.
Properties side by side
| Property | R-22 | R-407C |
|---|---|---|
| Type | HCFC | HFC blend |
| ASHRAE class | A1 | A1 |
| Composition | Pure | 23.0% R-32 / 25.0% R-125 / 52.0% R-134a |
| GWP (100-yr) | 1,810 | 1,774 |
| ODP | 0.055 | 0 |
| Lubricant | MO, AB | POE |
| Boiling point @ 1 atm | −40.8°C | −43.6°C |
| Critical point | 96.2°C / 709 PSIG | Blend (locus, not point) |
| Temp glide | 0.00°F | 11.02°F |
| AIM Act affected | No | Yes |
Choose R-22 if…
Servicing existing R-22 equipment with original R-22. Reclaimed R-22 remains legal under EPA rules. The lubricant (mineral oil) and equipment design stay matched to what was originally specified. Higher refrigerant cost is the trade-off.
Choose R-407C if…
Retrofitting an R-22 system where the oil-change procedure is acceptable and where the equipment owner wants to be off the increasingly-expensive reclaimed R-22 supply. R-407C delivers within 95% of R-22 capacity, operates at similar pressures, and uses commodity-priced HFC supply.
When neither is ideal
For systems requiring major work or 15+ years old, full system replacement with new R-32 or R-454B equipment is typically more cost-effective than R-22 service OR R-407C retrofit. New equipment is more efficient than R-22-era systems; new R-32 or R-454B equipment sits below the relevant 40 CFR 84.54 limit but remains a regulated HFC under the allowance phase-down, whereas R-407C (GWP 1,774) exceeds the 700-GWP limit for new residential and light-commercial AC and heat pumps (84.54(a)(1), (c)(1)).
Retrofit and transition
R-22 to R-407C is the most common R-22 retrofit path when oil change is acceptable. The procedure is well-documented and the capacity match is within 5% across typical operating conditions.
Retrofit procedure:
1. Recover R-22 to a dedicated R-22 recovery cylinder. Document recovered weight. 2. Remove mineral oil through 2-3 oil-change cycles. Each cycle: drain compressor crankcase, refill with POE oil of correct viscosity, run system briefly, drain again. Target residual mineral oil below 5% (verify with oil analysis if critical). 3. Replace filter-drier with HFC-compatible model (the desiccant in R-22-era driers may be incompatible with POE oil). 4. Pull vacuum to 500 microns and hold 30 minutes to verify dry, leak-tight system. 5. Charge R-407C by weight at approximately 95% of the original R-22 nameplate (R-407C is slightly more dense). For systems with significant line lengths, use the refrigerant charge calculator to adjust for line set. 6. Verify capacity at design conditions. Expect 90-95% of original R-22 capacity at the same ambient. 7. Adjust TXV if necessary — R-407C's 11°F temperature glide may require slight adjustment for stable operation.
Glide considerations. R-407C has substantial temperature glide (~11°F at typical evaporator pressures). For TXV systems this generally works without modification — the TXV controls to evaporator-outlet superheat which uses the dew curve naturally. For fixed-orifice systems the glide creates more variable operation across the evaporator; capacity is reduced ~5% compared to R-22 in fixed-orifice equipment.
Service measurement. Use the dew curve for superheat (suction-line measurement) and the bubble curve for subcooling (liquid-line measurement). The superheat calculator and subcooling calculator handle this automatically when R-407C is selected.
Regulatory and transition context
Both refrigerants sit in an active regulatory transition driven by climate-impact rules. The transitions affect availability, pricing, and new-equipment specification.
- AIM Act (40 CFR Part 84): US HFC production / import phase-down. Cap declines from 90% allocation (2022) to 15% by 2036. One or both refrigerants here are AIM Act-affected. US EPA restricts new residential and light-commercial air conditioners and heat pumps using a refrigerant of GWP 700 or more, effective January 1, 2025 (40 CFR 84.54(a)(1)). Limits for other equipment types differ.
- EU: Regulation (EU) No 517/2014, replaced by (EU) 2024/573 (applying from March 11, 2024); 2024/573 uses AR4 GWPs for HFCs and AR6 for other fluorinated gases (recital 8).
- Kigali Amendment to Montreal Protocol (2016): international HFC phase-down framework. The Montreal Protocol has 198 parties; 174 have ratified the Kigali Amendment (as of August 10, 2026). The AIM Act and EU F-Gas are regional implementations. Schedules differ by country group.
- ASHRAE 34-2022: safety classification (A1, A2L, A3, B1, B2L). For A2L refrigerants like R-32, R-454B, R-454C, R-455A: equipment must be A2L-certified, charge limits per IEC 60335-2-40 apply.
Standard transition procedure — R-22 → R-407C
Step-by-step service procedure for transitioning an existing R-22 system to R-407C, derived from the property differences above. Always cross-check equipment OEM service literature for the specific equipment being serviced. The steps below codify EPA Section 608 requirements (recovery, evacuation, documentation) plus refrigerant-specific accommodations for lubricant, safety class, pressure envelope, and glide differences. Skipping any of the regulatory steps (leak check, recovery, evacuation, documentation) creates compliance liability; skipping refrigerant-specific accommodations creates equipment-failure risk.
- Leak-check first. Verify the existing system isn't leaking before recharging. No general federal rule bars adding refrigerant to a leaking system; leak-repair duties apply by appliance size (40 CFR 82.157 for appliances with 50 lb or more of class I/II refrigerant, and 40 CFR 84.106 from January 1, 2026 for appliances with 15 lb or more of HFC refrigerant with GWP above 53).
- Recover R-22. Use a recovery machine rated for A1 refrigerants. Recover into properly-labeled cylinders; don't mix recovered R-22 with virgin or recovered R-407C (cross-contamination invalidates reclaim).
- Drain MO lubricant and flush. R-22 runs on MO/AB; R-407C requires POE. Drain the compressor crankcase, accumulator, and any oil traps. Flush the system with a compatible flush solvent or run POE lubricant through the system and re-drain to clear residual MO. Mixing mineral oil with POE in an HFC system produces oil-return failures within hours of operation.
- Replace filter-drier. Install a new drier rated for R-407C (POE lubricant). Filter-driers are single-use after exposure to a refrigerant; the old drier may have absorbed contaminants you don't want carrying into the new charge.
- Pressure-test and evacuate to ≤500 microns. Pressure-test with dry nitrogen to verify no leaks. Pull deep vacuum and hold ≥30 minutes with vacuum pump isolated to confirm no leak-back. This step is non-negotiable — non-condensables (air, moisture) trapped in the system raise discharge pressure and damage the compressor.
- Charge R-407C by weight to nameplate — adjusted for the +15% pressure difference vs R-22. Use a calibrated recovery / charging scale. Charging by gauge feel produces frequent overcharge errors.
- Verify with SH and SC at steady state. R-407C is zeotropic with 11.0°F glide — use the dew curve at suction for SH, bubble curve at discharge for SC. Wrong-curve selection introduces error equal to the glide. Target SC = 8-12°F for TXV systems; target SH per OEM nameplate.
- Document and label. Update the equipment data plate to reflect R-407C. EPA Section 608 requires records of refrigerant added / recovered; OEM warranty may require documentation of approved-refrigerant substitution.
Lifecycle and operational context
Beyond the per-service-call decision, the R-22 ↔ R-407C choice also involves regulatory and lifecycle factors. The transition direction (which is the predecessor, which is the successor) is driven by climate policy and the AIM Act phase-down, not technical preference alone.
- GWP profile: R-22 = 1,810 GWP; R-407C = 1,774 GWP. Switching from R-22 to R-407C reduces direct refrigerant climate impact by 2%.
- AIM Act exposure: R-407C is AIM Act-affected; R-22 is not — the transition increases regulatory exposure (unusual direction). One or both have a GWP of 700 or more: US EPA restricts new residential and light-commercial AC and heat pumps at that level, effective January 1, 2025 (40 CFR 84.54(a)(1)). Limits for other equipment types differ.
- EU (Regulation (EU) No 517/2014, replaced by (EU) 2024/573): R-22 (GWP 1,810) is below every Regulation (EU) No 517/2014 Annex III GWP threshold. R-407C (GWP 1,774) meets 2 Annex III placing-on-the-market prohibitions; the earliest is Refrigerators and freezers for commercial use (hermetically sealed equipment) (GWP ≥ 150) from January 1, 2022.
- Service supply outlook: Service supply of AIM Act-affected refrigerants persists during phase-down via reclaimed and allocated production, with prices rising as supply tightens. Plan for refrigerant cost escalation over equipment lifetime.
- TEWI / LCCP framing: Total Equivalent Warming Impact accounts for both direct refrigerant emissions (leakage, end-of-life) and indirect emissions from equipment energy consumption. For HVAC equipment with ≤5% annual leak rate, indirect emissions typically dominate TEWI by 80-90% — meaning equipment efficiency matters more than refrigerant GWP for total climate impact. For commercial refrigeration with higher leak rates, the balance can tip toward favoring low-GWP refrigerants.
Regulatory sources: AIM Act (40 CFR Part 84), EU F-Gas Regulation 517/2014 and update 2024/573, Kigali Amendment to the Montreal Protocol (2016). GWP values on the US EPA basis (40 CFR 84 / IPCC AR4).
Service implications — R-22 → R-407C
What a service technician needs to know when transitioning from R-22 to R-407C (or comparing them for new equipment specification). Two scenarios show how the difference affects a service call.
Pressure envelope check for R-22 → R-407C
Scenario · Field tech needs to know: do R-22 service tools handle R-407C, or does the pressure delta require new equipment? PT chart comparison at service temperatures gives the answer.
| Temp | R-22 | R-407C | Δ |
|---|---|---|---|
| 40°F | 69 PSIG | 80 PSIG | +17.0% |
| 70°F | 121 PSIG | 141 PSIG | +15.7% |
| 95°F | 182 PSIG | 209 PSIG | +15.2% |
Service-side implications: lubricant and safety
Scenario · Beyond pressure envelope, the switch from R-22 to R-407C affects lubricant, safety class, and operating procedure.
| Concern | R-22 | R-407C | Action |
|---|---|---|---|
| Lubricant | MO/AB | POE | Oil change required |
| Safety class | A1 | A1 | No change |
| Glide | 0.0°F | 11.0°F | Curve awareness |
When to use which tool for this comparison
- R-22 full reference — properties, PT chart, lubricant, retrofit options for R-22.
- R-407C full reference — properties, PT chart, lubricant, retrofit options for R-407C.
- PT Comparison Tool — overlay any 2-4 refrigerants' PT curves interactively.
- Retrofit Compatibility Calculator — five-criterion compatibility analysis with verdict.
- Refrigerant Comparison Guide — long-form sourced reference for all common HVAC refrigerant comparisons.
Frequently asked
›Can I add R-407C to a partially-charged R-22 system without recovering and recharging?
No. Mixing R-407C with R-22 produces a non-standard blend with unpredictable composition (R-407C is itself a blend that fractionates if charged as vapor). The mineral oil in the R-22 system is also incompatible with R-407C's required POE lubricant. Full recovery, oil change, vacuum, and recharge is mandatory for the retrofit to work reliably.
›What's R-407C's GWP and why does it matter?
GWP 1,774 — below R-22's 1,810 and below R-410A's 2,088, but well above modern low-GWP A2L alternatives. Under the AIM Act R-407C is restricted for many new equipment categories starting in 2025-2026. R-407C remains legal for service of existing equipment indefinitely, but for new R-22 retrofits the choice should account for the limited remaining regulatory runway of R-407C.
›Why does R-407C have temperature glide while R-22 has none?
R-22 is a pure refrigerant (single molecule, chlorodifluoromethane) — bubble and dew points are identical. R-407C is a ternary blend of R-32, R-125, and R-134a in 23/25/52 mass proportions; the components have different vapor pressures, so the blend has bubble (saturated liquid) and dew (saturated vapor) temperatures that differ by ~11°F at typical pressures. This is normal for zeotropic blends and is accounted for in TXV-based equipment design.
›Will my R-22 equipment work with R-407C?
Most R-22 equipment is compatible with R-407C with the oil change and filter-drier replacement described above. The pressure envelope is similar enough (R-407C is within about 15% of R-22) that R-22-rated components handle it. Check the equipment OEM's R-407C retrofit guidance — some specific equipment models have published retrofit procedures or restrictions.
›How much capacity will I lose with R-407C retrofit?
Typically 5-10%. R-407C has slightly lower volumetric capacity than R-22 at the same operating conditions. The reduction is more pronounced in fixed-orifice systems (because the glide affects evaporator behavior) than in TXV systems. For most residential and light commercial applications the capacity reduction is acceptable but worth verifying against the load.
›What lubricant does R-407C use?
Polyolester (POE) oil. Mineral oil and alkylbenzene (AB) are incompatible. The R-22 to R-407C retrofit requires oil change as documented in the procedure above. POE oil is hygroscopic — it absorbs water aggressively — so vacuum and filter-drier replacement are critical to prevent moisture damage.
Related
R-22 PT chart
Full reference: PT chart, properties, retrofit guidance.
R-407C PT chart
Full reference: PT chart, properties, retrofit guidance.
R-22 operating pressures
Suction/discharge ranges by ambient + diagnostic procedure.
R-407C operating pressures
Suction/discharge ranges by ambient + diagnostic procedure.