Consider the following:
Understand that R12 has its advantages. R12 can blow 6 to 7 degrees cooler than R134a and is 15% more efficient. R134a systems require larger condensers and higher operating pressures than R12 systems because R134a doesn't have as high of a heat transfer rate as R12 (which has a heavier molecular size than R134a).
Whether R134a performs as well as R12 in any given a/c system depends upon system components and the amount of R134a used.
Given two identical vehicles, each with the same weighted amount of refrigerant, the vehicle with the R134a has the “capability” to remove more heat (measured in btu’s) from the vehicle than the same type of vehicle using the same amount of R12.
The most common influences which effect the capability of R134a to perform well are the condenser, in some cases the the superheat setting of the expansion valve or the amount of R134a. Condensers designed to release greater amounts of heat help to expel the greater amount of heat which R134a removes from the car’s interior. And by “matching” the correct amount of R134a to use in a given vehicle, correcting the superheat of the expansion valve (if necessary), you can in some manner nearly balance or match the amount of heat drawn out by the evaporator and released by the condenser.
These efforts to “balance” the system can not be realized if there are problems within the a/c system, such as: poor performing compressor, dirty condenser or poor air flow through the condenser, malfunctioning expansion valve, water or air in the system, improperly operating fresh air or heat input in the climate-air mixing system.
Because of volume and pressure differences between the two refrigerants, the RV2 may not have sufficient displacement or volume capacity to maintain the R134A pressures and likely that the condenser will not have enough SURFACE AREA to dissipate the collected heat, and the EVAPORATOR will not have enough SURFACE AREA to absorb the heat. Likewise, the refrigerant metering device, thd thermoststic expansion valve or TXV, will not be compatible with R134A refrigerant. The new style AXIAL FLOW COMPRESSOR, such as the Sandun unit, is an excellent unit and can be adapted to suit the application. To achieve a coordinated system and maximum performance, the major components must be sized correctly.
An additional consideration must be given to the vehicles existing COOLING system.....radiator, water pump, shroud, engine fan. Just talking out loud......
BOB RENTON
