Home' Australian Automotive Aftermarket Magazine : Australian Auto Aftermarket E-zine December Contents TECHNICAL COLUMN
But all of this is about to be made more
complicated to protect the environment.
In Europe and USA, a new, low environmental
impact refrigerant is just about to hit the market
which will necessitate the duplication of servicing
equipment to support the transition from the
current R-134a refrigerant to its replacement, R-
The continual focus on reducing the carbon
footprint of mobility will impact on future Heating
Ventilation and Air Conditioning (HVAC) design
The fuel economy associated with these
creature comforts in a conventional vehicle is
around five to seven percent, which is significant
enough to justify ongoing research into efficiency
On the other hand, the move to electric
vehicles and hybrids presents its own problems.
Electric Vehicles (EV) have no internal
combustion engine to drive a compressor and
hybrids, where the engine shuts off to conserve
fuel, require an electric compressor to power the
air conditioning system.
For heating, where waste heat from an engine
is no longer available, electric vehicles use a
reverse cycle air conditioner.
But this can reduce the range of an EV or the
zero emission range of a hybrid by up to 35
percent and a number of research projects are
underway to minimise power usage while
maintaining passenger comfort.
This article will review the operation of air
conditioning, the changeover to new refrigerants
and future developments to improve the
efficiency of HVAC systems.
Air conditioning operation
You would have noticed when using an aerosol
can that the can gets cold when spraying.
This is due to the rapid expansion of the
compressed gas. This is the same principle used
in an automotive air conditioner.
A compressor, driven by the engine,
compresses a gas called a refrigerant resulting in
a rise in its temperature.
On passing through the condenser, located
near the radiator, heat is given off and the gas
condenses to a liquid form.
It then passes through the receiver-drier, a
filtering and storage device, and on to the
expansion valve which releases the correct
amount of gas through a small orifice.
The sudden pressure drop in the atomised
liquid gas causes its temperature to fall well
below that of the vehicle interior where it absorbs
heat through the evaporator core, vaporises to a
gaseous form, and returns to the compressor for
the cycle to be repeated.
Since the mid-nineties the refrigerant used in
automotive air conditioners has been R-134a
which replaced R12 to lower the potential for
global warming and ozone layer depletion.
Recently the EU introduced a new regulation
requiring cars sold in the EU to use refrigerants
with Global Warming Potential (GWP) less than
150 beginning in 2011 for new vehicles and in
2017 for all vehicles.
An approved replacement in Europe and USA
is R-1234yf, which is similar in performance but
has a vastly improved GWP rating of four
compared to the R-134a index of 1430 and has
an atmospheric lifetime of
around 11 days compared
to 12 years for its
Vehicle production has
already commenced in
Europe and USA albeit
delayed due to a supply
shortage from the supplier --
a joint venture between
Honeywell and Du Pont
which hold the patents for
the newly developed
According to industry
news reports, the only
supply of R-1234yf is
available from a pilot plant
built by Honeywell until a
joint venture plant being
built in China becomes
The new refrigerant is expensive, reputedly
around 10 times that of its predecessor, and
requires new recover/ recycle/ recharge
So in future there will be two different air
conditioner service units in workshops.
As R-1234yf is mildly flammable, the new
equipment will need to incorporate explosion
protection and as the chemical composition of
the two refrigerants is different, using the new
refrigerant in service units for R-143a could be
In addition, the new equipment will need to
meet stringent safety and operational standards.
Gas analysis using a Refrigerant Particulate
Analyser (RPA) is a mandatory requirement to
avoid mixing different refrigerants where servicing
is discontinued if a different refrigerant is
Automatic pressure testing of the equipment
components and the vehicle air conditioning
system prior to filling is also mandatory and the
fittings on the vehicle for R-1234yf will be
different to other refrigerants.
An obvious question is why not a combined
service unit? This would be very expensive as it
would need to integrate two totally separate
refrigerant cycles into the one unit.
Should one cycle fail the whole unit
would no longer be usable and excessive
downtime would result.
In addition, only one air conditioning
service could be carried out at a time and
besides, many workshops already have
an R-134a service unit.
The manufacture of vehicles with R-
134a will continue until the end of 2016
and, with a service life of around 15
years, the maintenance of these systems
will continue to at least 2031.
In the meantime, vehicles with the
new refrigerant will hit the market from
2013 and based on average vehicle life
of 10 years, a 50:50 mix should occur
It should also be noted that special
compressor oils have been developed for
R-1234yf vehicle air conditioners.
These are compatible with R-134a
systems but PAG oils for R-134a systems are not
approved for use with R-1234yf systems.
Award winning innovation
The latest Lexus GS 450h offers an
innovative air conditioning system known as S
flow technology to maintain optimum comfort
Automotive air conditioning
Just a few years ago air conditioning in cars was a high priced option. Today all
vehicles offer this comfort feature as standard equipment. Consequently, while the
fitment of aftermarket kits is now almost non-existent, the maintenance and repair of
air conditioning systems is now a major contributor to the aftermarket industry.
46 AUTOMOTIVE AFTERMARKET MAGAZINE DECEMBER 2012
Readers are invited to send technical
enquiries of a general nature to:
Links Archive Australian Automotive Aftermarket E-zine - Annual Performance Guide Navigation Previous Page Next Page