R-12 reads 9.1 psig at 0°F, 36.9 psig at 40°F and 116.9 psig at 100°F.
R-12 lookup
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R-12 at a glance
Safety group
A1
Type
CFC, single component
Composition
Dichlorodifluoromethane (CCl2F2), single component
GWP (100-yr)
10900 (AR4) · 10200 (AR5)
Lubricant
Mineral oil
Boiling point
-21.6°F at 1 atm
Critical temperature
233.5°F
Used in
Air conditioning in older vehicles (banned in new vehicles since 1994); Older household refrigerators, freezers and small hermetic systems; Older commercial refrigeration
R-12 is a Class I ozone-depleting CFC: US production and import ended Jan 1, 1996, apart from limited exemptions, so service supply comes from existing stocks, and EPA restricts its sale to certified technicians.
R-12 pressure-temperature table
Every 5°F shown. ″ Hg = inches of mercury vacuum.
R-12 saturation pressure, psig at sea level
°F
°C
psig
-40
-40.0
11.0″ Hg
-39
-39.4
10.5″ Hg
-38
-38.9
10.0″ Hg
-37
-38.3
9.5″ Hg
-36
-37.8
8.9″ Hg
-35
-37.2
8.4″ Hg
-34
-36.7
7.8″ Hg
-33
-36.1
7.3″ Hg
-32
-35.6
6.7″ Hg
-31
-35.0
6.1″ Hg
-30
-34.4
5.5″ Hg
-29
-33.9
4.9″ Hg
-28
-33.3
4.3″ Hg
-27
-32.8
3.7″ Hg
-26
-32.2
3.0″ Hg
-25
-31.7
2.4″ Hg
-24
-31.1
1.7″ Hg
-23
-30.6
1.0″ Hg
-22
-30.0
0.3″ Hg
-21
-29.4
0.2
-20
-28.9
0.6
-19
-28.3
0.9
-18
-27.8
1.3
-17
-27.2
1.6
-16
-26.7
2.0
-15
-26.1
2.4
-14
-25.6
2.8
-13
-25.0
3.2
-12
-24.4
3.6
-11
-23.9
4.0
-10
-23.3
4.5
-9
-22.8
4.9
-8
-22.2
5.3
-7
-21.7
5.8
-6
-21.1
6.2
-5
-20.6
6.7
-4
-20.0
7.2
-3
-19.4
7.6
-2
-18.9
8.1
-1
-18.3
8.6
0
-17.8
9.1
1
-17.2
9.6
2
-16.7
10.1
3
-16.1
10.7
4
-15.6
11.2
5
-15.0
11.8
6
-14.4
12.3
7
-13.9
12.9
8
-13.3
13.4
9
-12.8
14.0
10
-12.2
14.6
11
-11.7
15.2
12
-11.1
15.8
13
-10.6
16.4
14
-10.0
17.0
15
-9.4
17.7
16
-8.9
18.3
17
-8.3
19.0
18
-7.8
19.6
19
-7.2
20.3
20
-6.7
21.0
21
-6.1
21.7
22
-5.6
22.4
23
-5.0
23.1
24
-4.4
23.8
25
-3.9
24.6
26
-3.3
25.3
27
-2.8
26.1
28
-2.2
26.8
29
-1.7
27.6
30
-1.1
28.4
31
-0.6
29.2
32
0.0
30.0
33
0.6
30.8
34
1.1
31.6
35
1.7
32.5
36
2.2
33.4
37
2.8
34.2
38
3.3
35.1
39
3.9
36.0
40
4.4
36.9
41
5.0
37.8
42
5.6
38.7
43
6.1
39.7
44
6.7
40.6
45
7.2
41.6
46
7.8
42.6
47
8.3
43.6
48
8.9
44.6
49
9.4
45.6
50
10.0
46.6
51
10.6
47.6
52
11.1
48.7
53
11.7
49.8
54
12.2
50.9
55
12.8
52.0
56
13.3
53.1
57
13.9
54.2
58
14.4
55.3
59
15.0
56.5
60
15.6
57.6
61
16.1
58.8
62
16.7
60.0
63
17.2
61.2
64
17.8
62.4
65
18.3
63.7
66
18.9
64.9
67
19.4
66.2
68
20.0
67.5
69
20.6
68.8
70
21.1
70.1
71
21.7
71.4
72
22.2
72.7
73
22.8
74.1
74
23.3
75.5
75
23.9
76.8
76
24.4
78.2
77
25.0
79.7
78
25.6
81.1
79
26.1
82.5
80
26.7
84.0
81
27.2
85.5
82
27.8
87.0
83
28.3
88.5
84
28.9
90.0
85
29.4
91.6
86
30.0
93.2
87
30.6
94.7
88
31.1
96.3
89
31.7
98.0
90
32.2
99.6
91
32.8
101.3
92
33.3
102.9
93
33.9
104.6
94
34.4
106.3
95
35.0
108.0
96
35.6
109.8
97
36.1
111.5
98
36.7
113.3
99
37.2
115.1
100
37.8
116.9
101
38.3
118.8
102
38.9
120.6
103
39.4
122.5
104
40.0
124.4
105
40.6
126.3
106
41.1
128.2
107
41.7
130.2
108
42.2
132.1
109
42.8
134.1
110
43.3
136.1
111
43.9
138.1
112
44.4
140.2
113
45.0
142.3
114
45.6
144.3
115
46.1
146.4
116
46.7
148.6
117
47.2
150.7
118
47.8
152.9
119
48.3
155.1
120
48.9
157.3
121
49.4
159.5
122
50.0
161.8
123
50.6
164.0
124
51.1
166.3
125
51.7
168.6
126
52.2
171.0
127
52.8
173.3
128
53.3
175.7
129
53.9
178.1
130
54.4
180.5
131
55.0
183.0
132
55.6
185.5
133
56.1
187.9
134
56.7
190.5
135
57.2
193.0
136
57.8
195.6
137
58.3
198.2
138
58.9
200.8
139
59.4
203.4
140
60.0
206.0
141
60.6
208.7
142
61.1
211.4
143
61.7
214.2
144
62.2
216.9
145
62.8
219.7
146
63.3
222.5
147
63.9
225.3
148
64.4
228.1
149
65.0
231.0
150
65.6
233.9
151
66.1
236.8
152
66.7
239.8
153
67.2
242.8
154
67.8
245.8
155
68.3
248.8
156
68.9
251.8
157
69.4
254.9
158
70.0
258.0
159
70.6
261.1
160
71.1
264.3
Saturation pressures computed with CoolProp 8.0.0 (R12) on October 10, 2026, gauge pressure at sea level. Checked against Honeywell published chart at 8 points; largest difference 0.05 psi. How these numbers are made.
What R-12 is and where you still find it
R-12 is dichlorodifluoromethane, a chlorofluorocarbon (CFC) sold as Freon 12 by DuPont and as Genetron 12 by Honeywell. It is a single-component refrigerant with an ASHRAE A1 rating. EPA says it was widely used in car and truck air conditioning for over 30 years, up to the mid-1990s. Danfoss lists it among the refrigerants used in small hermetic systems such as household refrigerators and freezers, and EPA lists CFC-12 among the refrigerants that older commercial refrigeration relied on.
CFCs release chlorine that depletes stratospheric ozone, and they are controlled under the Montreal Protocol and phased out under the Clean Air Act. EPA lists the ozone depletion potential of CFC-12 as 1. US production and import of CFCs ended on Jan 1, 1996, apart from limited exemptions, and EPA says CFC-12 has been banned in new vehicles since 1994. EPA notes that some vehicles built before then may still use it if they have not been retrofitted.
How to read the R-12 chart
R-12 is a pure fluid, so one pressure goes with each temperature. Use the same value for superheat and subcooling:
Superheat: at 30 psig suction, saturation is 32.0°F. Use the superheat calculator.
Subcooling: at 150 psig liquid pressure, saturation is 116.7°F. Use the subcooling calculator.
R-12 boils at -21.6°F at atmospheric pressure, so below that temperature the low side goes into vacuum. At -20°F it reads only 0.6 psig.
R-12 and R-134a look alike in the middle of the chart (70.1 psig against 71.1 psig at 70°F), but they split apart at the ends. At a 130°F condensing temperature R-12 is 180.5 psig and R-134a is 198.7 psig. At -10°F R-12 is 4.5 psig and R-134a is 1.9 psig. At the same condensing temperature, R-134a runs a higher head pressure than R-12.
Typical R-12 pressures
As example saturation temperatures, not targets: a car AC evaporator near 35°F reads 32.5 psig, and a condenser at 130°F reads 180.5 psig. A household freezer evaporator at -10°F reads 4.5 psig, with a condenser at 100°F reading 116.9 psig. These are saturation values, not service targets. The vehicle or appliance service data governs.
Service and legal notes
Buying it. EPA requires technician certification to purchase CFC-12. Containers under 20 pounds may be sold only to Section 609 certified technicians. Car AC work for pay requires Section 609 certification and EPA-certified recovery equipment.
No venting. Section 608 of the Clean Air Act prohibits intentionally venting refrigerant, including from car AC. Recover R-12 with certified equipment. Recovered refrigerant must be recycled or reclaimed before it goes back into a vehicle.
Oil. Honeywell lists mineral oil for R-12. Arkema notes that mineral oil and alkylbenzene have poor miscibility with HFCs such as R-134a.
Converting a car. EPA allows retrofits only to SNAP-approved refrigerants such as R-134a. Remove all the R-12 with approved recovery equipment first. Fit the unique service fittings for the new refrigerant, with no adapters. Remove or completely cover the R-12 label and apply a new permanent label with the retrofit details, including who did the work, the date, and the type, maker and amount of lubricant. EPA does not treat any retrofit refrigerant as a drop-in.
No mixing. EPA requires each approved car AC refrigerant to use its own unique fittings so refrigerants are not mixed, and says an adapter should not be used to convert a fitting.