My understanding is that R-134 refrigerant has different thermodynamic properties and expands to a somewhat higher temperature than does R-12 from a given pressure. Newer cars adjust for that with larger evaporator coils and flow rates to achieve cooling but the outlet air temperature will never be 40F again. The capillary expansion tube is no-doubt different, also. Our ’99 Wrangler FA/C starts cooling immediately. Our ’05 Durango starts cooling slowly but eventually gets the job done. Both use R-134.
No doubt, R-12 was a great refrigerant for cars. Eventually, nearly all refrigerants will be vented to atmosphere. Some may be broken down but the chlorine will still go to the atmosphere and break down the ozone (O3) layer (or so they say). Changeover was on or about 1-1-94.
Rich Barber, BSME
The service manual states 45 ounces of R12 Freon is the capacity. My question is, since converting to R134 several years ago, is that still the correct number ? I think mine is running low and want to recharge as it is blowing cool but not cold as it should be.
--Ray Jones. Y'all come on down an see us. Ya hear?