R-407C Refrigerant
HFC blend designed as a non-ozone depleting alternative to R-22. Used in residential and light commercial air conditioning systems.
Significant Temperature Glide
R-407C has a 7-9°F temperature glide. Use bubble point for liquid line and dew point for suction line readings.
Blend Composition
Note: R-32 is mildly flammable (A2L), but the blend is classified A1
Physical Properties
R-407C vs R-22
R-407C Pressure-Temperature Chart
Important: R-407C is a zeotropic blend with significant glide (~7-9°F).
• Bubble Point = Liquid Line saturation (use for subcooling)
• Dew Point = Suction Line saturation (use for superheat)
| Temp °F | Temp °C | Bubble (psig) | Dew (psig) |
|---|---|---|---|
| -40°F | -40°C | -2.3 | 4.3 |
| -30°F | -34.4°C | 2.5 | 9.7 |
| -20°F | -28.9°C | 8 | 15.8 |
| -10°F | -23.3°C | 14.4 | 22.8 |
| 0°F | -17.8°C | 21.7 | 30.8 |
| 10°F | -12.2°C | 30 | 39.8 |
| 20°F | -6.7°C | 39.3 | 50 |
| 25°F | -3.9°C | 44.4 | 55.6 |
| 30°F | -1.1°C | 49.9 | 61.5 |
| 35°F | 1.7°C | 55.7 | 67.8 |
| 40°F | 4.4°C | 61.8 | 74.5 |
| 45°F | 7.2°C | 68.4 | 81.6 |
| 50°F | 10°C | 75.3 | 89.1 |
| 55°F | 12.8°C | 82.6 | 97 |
| 60°F | 15.6°C | 90.3 | 105.4 |
| 65°F | 18.3°C | 98.4 | 114.2 |
| 70°F | 21.1°C | 106.9 | 123.5 |
| 80°F | 26.7°C | 124.9 | 143.2 |
| 90°F | 32.2°C | 144.8 | 164.9 |
| 100°F | 37.8°C | 166.5 | 188.6 |
| 110°F | 43.3°C | 190.3 | 214.5 |
| 120°F | 48.9°C | 216.2 | 242.6 |
| 130°F | 54.4°C | 244.4 | 273.1 |
| 140°F | 60°C | 274.9 | 306.1 |
Understanding Temperature Glide
What is Temperature Glide?
In zeotropic blends like R-407C, the different component refrigerants evaporate and condense at different temperatures. This causes a temperature change during phase transition.
Bubble Point (Liquid)
Temperature where first vapor bubble forms. Use for liquid line readings and subcooling calculation.
Dew Point (Vapor)
Temperature where last liquid drop evaporates. Use for suction line readings and superheat calculation.
Practical Implications
- Counter-flow heat exchangers work best with glide refrigerants
- Flooded evaporators may have issues due to composition shift
- Must charge as liquid to prevent fractionation
- If significant leak occurs, entire charge should be replaced
R-22 to R-407C Retrofit Procedure
Recover All R-22
Completely recover existing R-22 refrigerant. System must be empty.
Replace Oil with POE
R-407C requires POE (Polyolester) oil. Mineral oil is not compatible. Drain existing oil and replace with manufacturer-specified POE oil.
Replace Filter Drier
Install new HFC-compatible filter drier. POE oil is hygroscopic and requires proper moisture control.
Replace or Adjust TXV
R-22 TXV must be replaced or adjusted for R-407C. May also need adjustment to superheat settings.
Check Gaskets and Seals
Verify all gaskets and o-rings are compatible with R-407C and POE oil.
Evacuate System
Deep vacuum to 500 microns or below. POE oil requires very dry system.
Charge with R-407C (Liquid)
Charge as liquid only. Expect approximately same charge weight as R-22.
Update Labels
Apply R-407C label and update unit nameplate. Never mix refrigerants.
Critical Warnings
- • Never mix R-22 and R-407C
- • System must be 100% purged before conversion
- • Expect 5-10% capacity reduction
- • Monitor discharge temperature (runs hotter)
- • Some older systems may not be suitable for retrofit
R-407C Operating Guidelines
Typical Pressures (AC Mode)
Suction (Low Side)
60-75 psig
At 40-45°F evaporator temp (dew point)
Discharge (High Side)
200-300 psig
Varies with ambient temperature
Charging Targets
Superheat (TXV System)
8-12°F
Use dew point for suction saturation
Subcooling
10-15°F
Use bubble point for liquid saturation
Special Considerations
- Charge as liquid only to prevent fractionation
- Monitor discharge temp - runs higher than R-22
- Use POE oil only - not compatible with mineral oil
- If major leak, replace entire charge
- POE oil is hygroscopic - minimize air exposure