Does anyone know the correct low side pressure after doing a R-134a retrofit from R-12? The R-12 specifications state 20-40 PSI and about 2 pounds of R-12. R-134a is typically 85% of that or 26-27 ounces however when I was adding the R-134a refrigerant the hose connection to the fitting was loose and lost, I estimate about 1/2 a 15 ounce can of refrigerant. I ma having dififculty in getting a measurement of the low pressure with the gauge I purchased. ANyway, if anyone knows what the retrofitted R-134a low side pressure should be please let me know. Thanks.