|liquid. The orifice expansion valve, or tube,
regulates the flow of high-pressure liquid refrigerant to the evaporator there by lowering
the pressure. The evaporator is then used to cool, dry and clean the air that enters the
passenger compartment. Lastly, the accumulator-dehydrator separates liquid refrigerant
from the gas stale before it enters the compressor and removes moisture from the system.
introduction of KFC R-134a refrigerant has solved the environmental problems of CFC R-12,
yet there are new issues, which have to be considered. Initial testing of HFC R-134a has
shown higher operating pressures than that of CFC R-12. The new gas R-134a is less active
than Freon R-12. This results in [he gas changing t o a liquid at a slower rate than R-12.
When retrofitting an existing R-12 system, we are now confronted with differences, which
have to be addressed.
VOLKSWAGEN AIR CONDITIONING SYSTEMS
From the later 1960s through the 198Os, VW air conditioners were notoriously poor
performing systems. This poses numerous problems for retrofit because of the basic key
components (condensers and evaporators) have poor heal dissipation characteristics. This
situation is enhanced with the use of R-134a which is not as active a gas as R-12.
On a VW the condensing is the primary concern when performing the R-134a upgrade. The
new design parallel flow condenser must be used along with high
An early '90s Jetta with the R-134a conversion, including receiver drier and auxiliary
condenser fan (arrows).
|capacity (airflow) cooling fan to ensure compressor head pressures are
kept within guidelines prescribed for R-134a. Refrigerant psi evaporator expansion valves
must also be replaced with larger orifice tubes to increase flow rate. This ensures
increased amounts of refrigerant to increase evaporator, performance.
The a/c hoses may
also need to be replaced with a new Barrier type. The new R-134a gas will permeate through
older a/c hoses. When upgrading your Volkswagen's system, check the hoses if they are
labeled Barrier, only Barrier type hoses will work with the R-134a systems. Earlier model
VWs did not have Barrier type hoses. Some air conditioning systems after they are upgraded
may vary 4-6 degrees higher vent outlet temperatures. Therefore it may be necessary to
dial in heat settings and expansion valve orifice sizes.
What does all this mean to the Volkswagen owner? If you plan on keeping your
vehicle for a few years, it may be necessary to upgrade your air conditioning system. If
your system is currently nut operating properly, you are a prime candidate to upgrade. The
cost of R-12 is now higher than R-134a and soon will be unavailable to recharge your
system after it is repaired. When the existing supply of R-12 is exhausted the demand for
upgrading will increase as will the price. The automotive industry predicts during the hot
summer months there will be waiting periods of 30 days or more to get your air conditioner
repaired or retrofitted. Upgrading your car's air conditioning will also increase its
In these changing times of heightened environmental consciousness, automobile air
conditioning must become environment tall y friendly to improve our global ecology.
One company that for 36 years has been providing air conditioning services and
equipment for all automobiles, including Volkswagens. I.C.E. Inc. 3275 Market Street.
Dept. HVWs, San Diego. CA 92102 (619) 338-9051. They will be providing both information
and data pertinent the environmentally safe retrofitting of air conditioners as well as
upgrade kits for all makes and models of cars, including all VWs.