A/C SYSTEM R-12/R-134-A NOMINAL PRESSURE INFORMATION
TECHNICAL SERVICE BULLETIN
Reference Number(s): 64 13 92 (3646)
NOMINAL AIR CONDITIONING SYSTEM PRESSURES R-12/R-134a

Model(s): All BMW Models

Group: 64 - Heating & Air Conditioning

Bulletin No.: 64 13 92 (3646)

Date: October, 1992
SITUATION

The following chart has been provided to assist the technician in determining the operational status of a BMW vehicle with a suspected air conditioning problem. The chart provides "nominal" values that approximate typical high side pressure, low side pressure, and center vent discharge temperature for a given ambient temperature, humidity, and refrigerant type. Note that the pressures given are directly dependent on the amount of refrigerant charge in the air conditioning system. If wide variation exists between the measured pressure values and those given on the chart, the technician should consider an overcharge/undercharge situation as a possible cause.

THIS INFORMATION IS CURRENT AND SUPERSEDES ALL OTHER SERVICE INFORMATION ON PRESSURE/TEMPERATURE/HUMIDITY RELATIONSHIPS FOR A/C SYSTEMS AS WELL AS ANY OTHER SOURCE OF SIMILAR INFORMATION.

AIR CONDITIONING SYSTEM PRESSURES R-12/R134A TABLE
Rel.Hum.(%) Outside Air Temp. (°F) R-12 Disch. Temp. (°F) R-12 Low Press. (psi) R-12 High Press. (psi) R-134a Disch. Temp. (°F) R-134 Low Press. (psi) R-134 High Press. (psi)
20 70 80 90 100 110 44 44 50 59 66 24 31 45 47 57 143 192 232 270 320 44 44 47 53 64 9 24 40 50 58 69 85 136 231 308
30 70 80 90 100 110 44 44 54 63 74 23 35 47 50 60 154 203 239 283 334 44 44 48 59 69 10 28 42 54 62 80 110 168 253 328
40 70 80 90 100 110 44 50 58 67 77 34 40 48 53 63 170 216 246 291 350 45 50 56 64 74 12 32 45 57 67 93 149 212 264 348
50 70 80 90 100 110 46 55 61 71 84 37 43 50 58 66 178 223 252 312 365 45 51 59 70 80 14 36 54 67 76 102 164 229 299 363
60 70 80 90 100 110 47 55 64 75 86 40 49 54 60 68 187 230 266 318 363 45 53 62 72 83 18 39 57 72 80 133 191 249 310 384
70 70 80 90 100 110 47 56 66 78 91 41 50 56 63 72 228 257 278 333 402 46 56 67 77 87 19 42 61 75 87 168 215 260 321 390
80 70 80 90 100 110 47 57 69 32 95 43 53 62 70 76 247 268 287 340 438 46 57 69 78 90 21 47 67 80 89 178 218 267 331 405
90 70 80 90 100 110 48 60 72 85 101 44 55 63 72 80 258 286 307 350 463 46 59 71 84 97 33 54 69 84 94 183 223 274 345 424